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diff --git a/erts/doc/src/crash_dump.xml b/erts/doc/src/crash_dump.xml index 61c9159823..a9aeb1888c 100644 --- a/erts/doc/src/crash_dump.xml +++ b/erts/doc/src/crash_dump.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>1999</year><year>2013</year> + <year>1999</year><year>2016</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -22,7 +22,7 @@ </legalnotice> - <title>How to interpret the Erlang crash dumps</title> + <title>How to Interpret the Erlang Crash Dumps</title> <prepared>Patrik Nyblom</prepared> <responsible></responsible> <docno></docno> @@ -32,401 +32,529 @@ <rev>PA1</rev> <file>crash_dump.xml</file> </header> - <p>This document describes the <c><![CDATA[erl_crash.dump]]></c> file generated - upon abnormal exit of the Erlang runtime system.</p> - <p><em>Important:</em> For OTP release R9C the Erlang crash dump has - had a major facelift. This means that the information in this - document will not be directly applicable for older dumps. However, - if you use the Crashdump Viewer tool on older dumps, the crash - dumps are translated into a format similar to this.</p> - <p>The system will write the crash dump in the current directory of + <p>This section describes the <c><![CDATA[erl_crash.dump]]></c> file + generated upon abnormal exit of the Erlang runtime system.</p> + + <note> + <p>The Erlang crash dump had a major facelift in Erlang/OTP R9C. The + information in this section is therefore not directly applicable for + older dumps. However, if you use <seealso marker="observer:crashdump_viewer"> + <c>crashdump_viewer(3)</c></seealso> on older dumps, + the crash dumps are translated into a format similar to this.</p> + </note> + + <p>The system writes the crash dump in the current directory of the emulator or in the file pointed out by the environment variable (whatever that means on the current operating system) - ERL_CRASH_DUMP. For a crash dump to be written, there has to be a - writable file system mounted.</p> + <c>ERL_CRASH_DUMP</c>. For a crash dump to be written, a + writable file system must be mounted.</p> + <p>Crash dumps are written mainly for one of two reasons: either the - builtin function <c><![CDATA[erlang:halt/1]]></c> is called explicitly with a - string argument from running Erlang code, or else the runtime + built-in function <c><![CDATA[erlang:halt/1]]></c> is called explicitly + with a string argument from running Erlang code, or the runtime system has detected an error that cannot be handled. The most - usual reason that the system can't handle the error is that the + usual reason that the system cannot handle the error is that the cause is external limitations, such as running out of memory. A - crash dump due to an internal error may be caused by the system + crash dump caused by an internal error can be caused by the system reaching limits in the emulator itself (like the number of atoms - in the system, or too many simultaneous ets tables). Usually the + in the system, or too many simultaneous ETS tables). Usually the emulator or the operating system can be reconfigured to avoid the crash, which is why interpreting the crash dump correctly is important.</p> + <p>On systems that support OS signals, it is also possible to stop - the runtime system and generate a crash dump by sending the SIGUSR1.</p> - <p>The erlang crash dump is a readable text file, but it might not be - very easy to read. Using the Crashdump Viewer tool in the - <c><![CDATA[observer]]></c> application will simplify the task. This is an - wx-widget based tool for browsing Erlang crash dumps.</p> + the runtime system and generate a crash dump by sending the <c>SIGUSR1</c> + signal.</p> + + <p>The Erlang crash dump is a readable text file, but it can be difficult + to read. Using the Crashdump Viewer tool in the + <c><![CDATA[Observer]]></c> application simplifies the task. This is a + wx-widget-based tool for browsing Erlang crash dumps.</p> <section> <marker id="general_info"></marker> - <title>General information</title> - <p>The first part of the dump shows the creation time for the dump, - a slogan indicating the reason for the dump, the system version, - of the node from which the dump originates, the compile time of - the emulator running the originating node, the number of - atoms in the atom table and the runtime system thread that caused - the crash dump to happen. - </p> + <title>General Information</title> + <p>The first part of the crash dump shows the following:</p> + + <list type="bulleted"> + <item>The creation time for the dump</item> + <item>A slogan indicating the reason for the dump</item> + <item>The system version of the node from which the dump originates</item> + <item>The compile time of the emulator running the originating node</item> + <item>The number of atoms in the atom table</item> + <item>The runtime system thread that caused the crash dump</item> + </list> <section> - <title>Reasons for crash dumps (slogan)</title> - <p>The reason for the dump is noted in the beginning of the file - as <em>Slogan: <reason></em> (the word "slogan" has historical - roots). If the system is halted by the BIF + <title>Reasons for Crash Dumps (Slogan)</title> + <p>The reason for the dump is shown in the beginning of the file as:</p> + + <pre> +Slogan: <reason></pre> + + <p>If the system is halted by the BIF <c><![CDATA[erlang:halt/1]]></c>, the slogan is the string parameter passed to the BIF, otherwise it is a description generated by the emulator or the (Erlang) kernel. Normally the message - should be enough to understand the problem, but nevertheless - some messages are described here. Note however that the - suggested reasons for the crash are <em>only suggestions</em>. The exact reasons for the errors may vary + is enough to understand the problem, but + some messages are described here. Notice that the + suggested reasons for the crash are <em>only suggestions</em>. + The exact reasons for the errors can vary depending on the local applications and the underlying operating system.</p> - <list type="bulleted"> - <item>"<em><A></em>: Cannot allocate <em><N></em> - bytes of memory (of type "<em><T></em>")." - The system - has run out of memory. <A> is the allocator that failed - to allocate memory, <N> is the number of bytes that - <A> tried to allocate, and <T> is the memory block - type that the memory was needed for. The most common case is - that a process stores huge amounts of data. In this case - <T> is most often <c><![CDATA[heap]]></c>, <c><![CDATA[old_heap]]></c>, - <c><![CDATA[heap_frag]]></c>, or <c><![CDATA[binary]]></c>. For more information on - allocators see - <seealso marker="erts_alloc">erts_alloc(3)</seealso>.</item> - <item>"<em><A></em>: Cannot reallocate <em><N></em> - bytes of memory (of type "<em><T></em>")." - Same as - above with the exception that memory was being reallocated - instead of being allocated when the system ran out of memory.</item> - <item>"Unexpected op code <em>N</em>" - Error in compiled - code, <c><![CDATA[beam]]></c> file damaged or error in the compiler.</item> - <item>"Module <em>Name</em> undefined" <c><![CDATA[|]]></c> "Function - <em>Name</em> undefined" <c><![CDATA[|]]></c> "No function - <em>Name</em>:<em>Name</em>/1" <c><![CDATA[|]]></c> "No function - <em>Name</em>:start/2" - The kernel/stdlib applications are - damaged or the start script is damaged.</item> - <item>"Driver_select called with too large file descriptor - <c><![CDATA[N]]></c>" - The number of file descriptors for sockets - exceed 1024 (Unix only). The limit on file-descriptors in - some Unix flavors can be set to over 1024, but only 1024 - sockets/pipes can be used simultaneously by Erlang (due to - limitations in the Unix <c><![CDATA[select]]></c> call). The number of - open regular files is not affected by this.</item> - <item>"Received SIGUSR1" - Sending the SIGUSR1 signal to a - Erlang machine (Unix only) forces a crash dump. This slogan reflects - that the Erlang machine crash-dumped due to receiving that signal.</item> - <item>"Kernel pid terminated (<em>Who</em>) - (<em>Exit-reason</em>)" - The kernel supervisor has detected - a failure, usually that the <c><![CDATA[application_controller]]></c> - has shut down (<c><![CDATA[Who]]></c> = <c><![CDATA[application_controller]]></c>, - <c><![CDATA[Why]]></c> = <c><![CDATA[shutdown]]></c>). The application controller - may have shut down for a number of reasons, the most usual - being that the node name of the distributed Erlang node is - already in use. A complete supervisor tree "crash" (i.e., - the top supervisors have exited) will give about the same - result. This message comes from the Erlang code and not from - the virtual machine itself. It is always due to some kind of - failure in an application, either within OTP or a - "user-written" one. Looking at the error log for your - application is probably the first step to take.</item> - <item>"Init terminating in do_boot ()" - The primitive Erlang boot - sequence was terminated, most probably because the boot - script has errors or cannot be read. This is usually a - configuration error - the system may have been started with - a faulty <c><![CDATA[-boot]]></c> parameter or with a boot script from - the wrong version of OTP.</item> - <item>"Could not start kernel pid (<em>Who</em>) ()" - One of the - kernel processes could not start. This is probably due to - faulty arguments (like errors in a <c><![CDATA[-config]]></c> argument) - or faulty configuration files. Check that all files are in - their correct location and that the configuration files (if - any) are not damaged. Usually there are also messages - written to the controlling terminal and/or the error log - explaining what's wrong.</item> - </list> - <p>Other errors than the ones mentioned above may occur, as the - <c><![CDATA[erlang:halt/1]]></c> BIF may generate any message. If the + + <taglist> + <tag><em><A>: Cannot allocate <N> bytes of memory (of type + "<T>")</em></tag> + <item> + <p>The system has run out of memory. <A> is the allocator that + failed to allocate memory, <N> is the number of bytes that + <A> tried to allocate, and <T> is the memory block + type that the memory was needed for. The most common case is + that a process stores huge amounts of data. In this case + <T> is most often <c><![CDATA[heap]]></c>, + <c><![CDATA[old_heap]]></c>, <c><![CDATA[heap_frag]]></c>, or + <c><![CDATA[binary]]></c>. For more information on allocators, see + <seealso marker="erts_alloc"><c>erts_alloc(3)</c></seealso>.</p> + </item> + <tag><em><A>: Cannot reallocate <N> bytes of memory (of + type "<T>")</em></tag> + <item> + <p>Same as above except that memory was reallocated + instead of allocated when the system ran out of memory.</p> + </item> + <tag><em>Unexpected op code <N></em></tag> + <item> + <p>Error in compiled code, <c><![CDATA[beam]]></c> file damaged, or + error in the compiler.</p> + </item> + <tag><em>Module <Name> undefined <c><![CDATA[|]]></c> Function + <Name> undefined <c><![CDATA[|]]></c> No function + <Name>:<Name>/1 <c><![CDATA[|]]></c> No function + <Name>:start/2</em></tag> + <item> + <p>The Kernel/STDLIB applications are + damaged or the start script is damaged.</p> + </item> + <tag><em>Driver_select called with too large file descriptor + <c><![CDATA[N]]></c></em></tag> + <item> + <p>The number of file descriptors for sockets + exceeds 1024 (Unix only). The limit on file descriptors in + some Unix flavors can be set to over 1024, but only 1024 + sockets/pipes can be used simultaneously by Erlang (because of + limitations in the Unix <c><![CDATA[select]]></c> call). The number + of open regular files is not affected by this.</p> + </item> + <tag><em>Received SIGUSR1</em></tag> + <item> + <p>Sending the <c>SIGUSR1</c> signal to an Erlang machine (Unix only) + forces a crash dump. This slogan reflects that the Erlang machine + crash-dumped because of receiving that signal.</p> + </item> + <tag><em>Kernel pid terminated (<Who>) (<Exit + reason>)</em></tag> + <item> + <p>The kernel supervisor has detected a failure, usually that the + <c><![CDATA[application_controller]]></c> has shut down + (<c><![CDATA[Who]]></c> = <c><![CDATA[application_controller]]></c>, + <c><![CDATA[Why]]></c> = <c><![CDATA[shutdown]]></c>). + The application controller + can have shut down for many reasons, the most usual + is that the node name of the distributed Erlang node is + already in use. A complete supervisor tree "crash" (that is, + the top supervisors have exited) gives about the same + result. This message comes from the Erlang code and not from + the virtual machine itself. It is always because of some + failure in an application, either within OTP or a + "user-written" one. Looking at the error log for your + application is probably the first step to take.</p> + </item> + <tag><em>Init terminating in do_boot ()</em></tag> + <item> + <p>The primitive Erlang boot sequence was terminated, most probably + because the boot script has errors or cannot be read. This is + usually a configuration error; the system can have been started + with a faulty <c><![CDATA[-boot]]></c> parameter or with a boot + script from the wrong OTP version.</p> + </item> + <tag><em>Could not start kernel pid (<Who>) ()</em></tag> + <item> + <p>One of the kernel processes could not start. This is probably + because of faulty arguments (like errors in a + <c><![CDATA[-config]]></c> argument) + or faulty configuration files. Check that all files are in + their correct location and that the configuration files (if + any) are not damaged. Usually messages are also + written to the controlling terminal and/or the error log + explaining what is wrong.</p> + </item> + </taglist> + + <p>Other errors than these can occur, as the + <c><![CDATA[erlang:halt/1]]></c> BIF can generate any message. If the message is not generated by the BIF and does not occur in the - list above, it may be due to an error in the emulator. There - may however be unusual messages that I haven't mentioned, that - still are connected to an application failure. There is a lot - more information available, so more thorough reading of the - crash dump may reveal the crash reason. The size of processes, - the number of ets tables and the Erlang data on each process - stack can be useful for tracking down the problem.</p> + list above, it can be because of an error in the emulator. There + can however be unusual messages, not mentioned here, which + are still connected to an application failure. There is much + more information available, so a thorough reading of the + crash dump can reveal the crash reason. The size of processes, + the number of ETS tables, and the Erlang data on each process + stack can be useful to find the problem.</p> </section> <section> - <title>Number of atoms</title> + <title>Number of Atoms</title> <p>The number of atoms in the system at the time of the crash is shown as <em>Atoms: <number></em>. Some ten thousands atoms is - perfectly normal, but more could indicate that the BIF - <c><![CDATA[erlang:list_to_atom/1]]></c> is used to dynamically generate a - lot of <em>different</em> atoms, which is never a good idea.</p> + perfectly normal, but more can indicate that the BIF + <c><![CDATA[erlang:list_to_atom/1]]></c> is used to generate many + <em>different</em> atoms dynamically, which is never a good idea.</p> </section> </section> <section> <marker id="scheduler"></marker> - <title>Scheduler information</title> - <p>Under the tag <em>=scheduler</em> information about the current state - and statistics of the schedulers in the runtime system is displayed. - On OSs that do allow instant suspension of other threads, the data within - this section will reflect what the runtime system looks like at the moment - when the crash happens.</p> + <title>Scheduler Information</title> + <p>Under the tag <em>=scheduler</em> is shown information about the current + state and statistics of the schedulers in the runtime system. On + operating systems that allow suspension of other threads, the + data within this section reflects what the runtime system looks like + when a crash occurs.</p> + <p>The following fields can exist for a process:</p> + <taglist> <tag><em>=scheduler:id</em></tag> - <item>Header, states the scheduler identifier.</item> + <item> + <p>Heading. States the scheduler identifier.</p> + </item> <tag><em>Scheduler Sleep Info Flags</em></tag> - <item>If empty the scheduler was doing some work. - If not empty the scheduler is either in some state of sleep, - or suspended. This entry is only present in a SMP enabled emulator</item> + <item> + <p>If empty, the scheduler was doing some work. + If not empty, the scheduler is either in some state of sleep, + or suspended. This entry is only present in an SMP-enabled + emulator.</p> + </item> <tag><em>Scheduler Sleep Info Aux Work</em></tag> - <item>If not empty, a scheduler internal auxiliary work is scheduled - to be done.</item> + <item> + <p>If not empty, a scheduler internal auxiliary work is scheduled + to be done.</p> + </item> <tag><em>Current Port</em></tag> - <item>The port identifier of the port that is currently being - executed by the scheduler.</item> + <item> + <p>The port identifier of the port that is currently + executed by the scheduler.</p> + </item> <tag><em>Current Process</em></tag> - <item>The process identifier of the process that is currently being - executed by the scheduler. If there is such a process this entry is - followed by the <em>State</em>,<em>Internal State</em>, - <em>Program Counter</em>, <em>CP</em> of that same process. See - <seealso marker="#processes">Process Information</seealso> for a - description what the different entries mean. Keep in mind that - this is a snapshot of what the entries are exactly when the crash - dump is starting to be generated. Therefore they will most likely - be different (and more telling) then the entries for the same - processes found in the <em>=proc</em> section. If there is no currently - running process, only the <em>Current Process</em> entry will be printed. + <item> + <p>The process identifier of the process that is currently + executed by the scheduler. If there is such a process, this entry is + followed by the <em>State</em>, <em>Internal State</em>, + <em>Program Counter</em>, and <em>CP</em> of that same process. + The entries are described in section + <seealso marker="#processes">Process Information</seealso>.</p> + <p>Notice that this is a snapshot of what the entries are exactly when + the crash dump is starting to be generated. Therefore they are most + likely different (and more telling) than the entries for the same + processes found in the <em>=proc</em> section. If there is no + currently running process, only the <em>Current Process</em> entry is + shown.</p> </item> <tag><em>Current Process Limited Stack Trace</em></tag> - <item>This entry only shows up if there is a current process. It is very - similar to <seealso marker="#proc_data"><em>=proc_stack</em></seealso>, - except that only the function frames are printed (i.e. the stack variables - are omited). It is also limited to only print the top and bottom part - of the stack. If the stack is small (less that 512 slots) then the - entire stack will be printed. If not, an entry stating - <code>skipping ## slots</code> will be printed where ## is - replaced by the number of slots that has been skipped.</item> + <item> + <p>This entry is shown only if there is a current process. It is + similar to <seealso marker="#proc_data"> + <em>=proc_stack</em></seealso>, except that only the function frames + are shown (that is, the stack variables are omitted). + Also, only the top and bottom part of the stack are shown. If the + stack is small (< 512 slots), the entire stack is shown. Otherwise + the entry <em>skipping ## slots</em> is shown, where <c>##</c> + is replaced by the number of slots that has been skipped.</p> + </item> <tag><em>Run Queue</em></tag> - <item>Displays statistics about how many processes and ports - of different priorities are scheduled on this scheduler.</item> + <item> + <p>Shows statistics about how many processes and ports + of different priorities are scheduled on this scheduler.</p> + </item> <tag><em>** crashed **</em></tag> - <item>This entry is normally not printed. It signifies that getting - the rest of the information about this scheduler failed for some reason. + <item> + <p>This entry is normally not shown. It signifies that getting the rest + of the information about this scheduler failed for some reason.</p> </item> </taglist> </section> <section> <marker id="memory"></marker> - <title>Memory information</title> - <p>Under the tag <em>=memory</em> you will find information similar - to what you can obtain on a living node with - <seealso marker="erts:erlang#erlang:memory/0">erlang:memory()</seealso>.</p> + <title>Memory Information</title> + <p>Under the tag <em>=memory</em> is shown information similar + to what can be obtainted on a living node with + <seealso marker="erts:erlang#erlang:memory/0"> + <c>erlang:memory()</c></seealso>.</p> </section> <section> <marker id="internal_tables"></marker> - <title>Internal table information</title> - <p>The tags <em>=hash_table:<table_name></em> and - <em>=index_table:<table_name></em> presents internal - tables. These are mostly of interest for runtime system - developers.</p> + <title>Internal Table Information</title> + <p>Under the tags <em>=hash_table:<table_name></em> and + <em>=index_table:<table_name></em> is shown internal + tables. These are mostly of interest for runtime system developers.</p> </section> <section> <marker id="allocated_areas"></marker> - <title>Allocated areas</title> - <p>Under the tag <em>=allocated_areas</em> you will find information - similar to what you can obtain on a living node with - <seealso marker="erts:erlang#system_info_allocated_areas">erlang:system_info(allocated_areas)</seealso>.</p> + <title>Allocated Areas</title> + <p>Under the tag <em>=allocated_areas</em> is shown information + similar to what can be obtained on a living node with + <seealso marker="erts:erlang#system_info_allocated_areas"> + <c>erlang:system_info(allocated_areas)</c></seealso>.</p> </section> <section> <marker id="allocator"></marker> <title>Allocator</title> - <p>Under the tag <em>=allocator:<A></em> you will find + <p>Under the tag <em>=allocator:<A></em> is shown various information about allocator <A>. The information - is similar to what you can obtain on a living node with - <seealso marker="erts:erlang#system_info_allocator_tuple">erlang:system_info({allocator, <A>})</seealso>. - For more information see the documentation of - <seealso marker="erts:erlang#system_info_allocator_tuple">erlang:system_info({allocator, <A>})</seealso>, - and the - <seealso marker="erts_alloc">erts_alloc(3)</seealso> - documentation.</p> + is similar to what can be obtained on a living node with + <seealso marker="erts:erlang#system_info_allocator_tuple"> + <c>erlang:system_info({allocator, <A>})</c></seealso>. + For more information, see also + <seealso marker="erts_alloc"><c>erts_alloc(3)</c></seealso>.</p> </section> <section> <marker id="processes"></marker> - <title>Process information</title> + <title>Process Information</title> <p>The Erlang crashdump contains a listing of each living Erlang - process in the system. The process information for one process - may look like this (line numbers have been added): - </p> - <p>The following fields can exist for a process:</p> + process in the system. The following fields can exist for a process:</p> + <taglist> <tag><em>=proc:<pid></em></tag> - <item>Heading, states the process identifier</item> + <item> + <p>Heading. States the process identifier.</p> + </item> <tag><em>State</em></tag> <item> <p>The state of the process. This can be one of the following:</p> - <list type="bulleted"> - <item><em>Scheduled</em> - The process was scheduled to run - but not currently running ("in the run queue").</item> - <item><em>Waiting</em> - The process was waiting for - something (in <c><![CDATA[receive]]></c>).</item> - <item><em>Running</em> - The process was currently - running. If the BIF <c><![CDATA[erlang:halt/1]]></c> was called, this was - the process calling it.</item> - <item><em>Exiting</em> - The process was on its way to - exit.</item> - <item><em>Garbing</em> - This is bad luck, the process was - garbage collecting when the crash dump was written, the rest - of the information for this process is limited.</item> - <item><em>Suspended</em> - The process is suspended, either - by the BIF <c><![CDATA[erlang:suspend_process/1]]></c> or because it is - trying to write to a busy port.</item> - </list> + <taglist> + <tag><em>Scheduled</em></tag> + <item>The process was scheduled to run + but is currently not running ("in the run queue").</item> + <tag><em>Waiting</em></tag> + <item>The process was waiting for + something (in <c><![CDATA[receive]]></c>).</item> + <tag><em>Running</em></tag> + <item>The process was currently running. + If the BIF <c><![CDATA[erlang:halt/1]]></c> was called, this was + the process calling it.</item> + <tag><em>Exiting</em></tag> + <item>The process was on its way to exit.</item> + <tag><em>Garbing</em></tag> + <item>This is bad luck, the process was + garbage collecting when the crash dump was written. The rest + of the information for this process is limited.</item> + <tag><em>Suspended</em></tag> + <item>The process is suspended, either + by the BIF <c><![CDATA[erlang:suspend_process/1]]></c> or because + it tries to write to a busy port.</item> + </taglist> </item> <tag><em>Registered name</em></tag> - <item>The registered name of the process, if any.</item> + <item> + <p>The registered name of the process, if any.</p> + </item> <tag><em>Spawned as</em></tag> - <item>The entry point of the process, i.e., what function was - referenced in the <c><![CDATA[spawn]]></c> or <c><![CDATA[spawn_link]]></c> call that - started the process.</item> + <item> + <p>The entry point of the process, that is, what function was + referenced in the <c><![CDATA[spawn]]></c> or + <c><![CDATA[spawn_link]]></c> call that + started the process.</p> + </item> <tag><em>Last scheduled in for | Current call</em></tag> - <item>The current function of the process. These fields will not - always exist.</item> + <item> + <p>The current function of the process. These fields do not + always exist.</p> + </item> <tag><em>Spawned by</em></tag> - <item>The parent of the process, i.e. the process which executed - <c><![CDATA[spawn]]></c> or <c><![CDATA[spawn_link]]></c>.</item> + <item> + <p>The parent of the process, that is, the process that executed + <c><![CDATA[spawn]]></c> or <c><![CDATA[spawn_link]]></c>.</p> + </item> <tag><em>Started</em></tag> - <item>The date and time when the process was started.</item> + <item> + <p>The date and time when the process was started.</p> + </item> <tag><em>Message queue length</em></tag> - <item>The number of messages in the process' message queue.</item> + <item> + <p>The number of messages in the process' message queue.</p> + </item> <tag><em>Number of heap fragments</em></tag> - <item>The number of allocated heap fragments.</item> + <item> + <p>The number of allocated heap fragments.</p> + </item> <tag><em>Heap fragment data</em></tag> - <item>Size of fragmented heap data. This is data either created by - messages being sent to the process or by the Erlang BIFs. This - amount depends on so many things that this field is utterly - uninteresting.</item> + <item> + <p>Size of fragmented heap data. This is data either created by + messages sent to the process or by the Erlang BIFs. This + amount depends on so many things that this field is utterly + uninteresting.</p> + </item> <tag><em>Link list</em></tag> - <item>Process id's of processes linked to this one. May also contain - ports. If process monitoring is used, this field also tells in - which direction the monitoring is in effect, i.e., a link - being "to" a process tells you that the "current" process was - monitoring the other and a link "from" a process tells you - that the other process was monitoring the current one.</item> + <item> + <p>Process IDs of processes linked to this one. Can also contain + ports. If process monitoring is used, this field also tells in + which direction the monitoring is in effect. That is, a link + "to" a process tells you that the "current" process was + monitoring the other, and a link "from" a process tells you + that the other process was monitoring the current one.</p> + </item> <tag><em>Reductions</em></tag> - <item>The number of reductions consumed by the process.</item> + <item> + <p>The number of reductions consumed by the process.</p> + </item> <tag><em>Stack+heap</em></tag> - <item>The size of the stack and heap (they share memory segment)</item> + <item> + <p>The size of the stack and heap (they share memory segment).</p> + </item> <tag><em>OldHeap</em></tag> - <item>The size of the "old heap". The Erlang virtual machine uses - generational garbage collection with two generations. There is - one heap for new data items and one for the data that have - survived two garbage collections. The assumption (which is - almost always correct) is that data that survive two garbage - collections can be "tenured" to a heap more seldom garbage - collected, as they will live for a long period. This is a - quite usual technique in virtual machines. The sum of the - heaps and stack together constitute most of the process's - allocated memory.</item> + <item> + <p>The size of the "old heap". The Erlang virtual machine uses + generational garbage collection with two generations. There is + one heap for new data items and one for the data that has + survived two garbage collections. The assumption (which is + almost always correct) is that data surviving two garbage + collections can be "tenured" to a heap more seldom garbage + collected, as they will live for a long period. This is a + usual technique in virtual machines. The sum of the + heaps and stack together constitute most of the + allocated memory of the process.</p> + </item> <tag><em>Heap unused, OldHeap unused</em></tag> - <item>The amount of unused memory on each heap. This information is - usually useless.</item> - <tag><em>Stack</em></tag> - <item>If the system uses shared heap, the fields - <em>Stack+heap</em>, <em>OldHeap</em>, <em>Heap unused</em> - and <em>OldHeap unused</em> do not exist. Instead this field - presents the size of the process' stack.</item> + <item> + <p>The amount of unused memory on each heap. This information is + usually useless.</p> + </item> <tag><em>Memory</em></tag> - <item>The total memory used by this process. This includes call stack, - heap and internal structures. Same as <seealso marker="erlang#process_info-2">erlang:process_info(Pid,memory)</seealso>. + <item> + <p>The total memory used by this process. This includes call stack, + heap, and internal structures. Same as + <seealso marker="erlang#process_info-2"> + <c>erlang:process_info(Pid,memory)</c></seealso>.</p> </item> <tag><em>Program counter</em></tag> - <item>The current instruction pointer. This is only interesting for - runtime system developers. The function into which the program - counter points is the current function of the process.</item> + <item> + <p>The current instruction pointer. This is only of interest for + runtime system developers. The function into which the program + counter points is the current function of the process.</p> + </item> <tag><em>CP</em></tag> - <item>The continuation pointer, i.e. the return address for the - current call. Usually useless for other than runtime system - developers. This may be followed by the function into which - the CP points, which is the function calling the current - function.</item> + <item> + <p>The continuation pointer, that is, the return address for the + current call. Usually useless for other than runtime system + developers. This can be followed by the function into which + the CP points, which is the function calling the current + function.</p> + </item> <tag><em>Arity</em></tag> - <item>The number of live argument registers. The argument registers, - if any are live, will follow. These may contain the arguments - of the function if they are not yet moved to the stack.</item> - <item><em>Internal State</em></item> - <item>A more detailed internal represantation of the state of - this process.</item> + <item> + <p>The number of live argument registers. The argument registers + if any are live will follow. These can contain the arguments + of the function if they are not yet moved to the stack.</p> + </item> + <tag><em>Internal State</em></tag> + <item> + <p>A more detailed internal representation of the state of + this process.</p> + </item> </taglist> - <p>See also the section about <seealso marker="#proc_data">process data</seealso>.</p> + <p>See also section <seealso marker="#proc_data">Process Data</seealso>.</p> </section> <section> <marker id="ports"></marker> - <title>Port information</title> + <title>Port Information</title> <p>This section lists the open ports, their owners, any linked - processed, and the name of their driver or external process.</p> + processes, and the name of their driver or external process.</p> </section> <section> <marker id="ets_tables"></marker> - <title>ETS tables</title> + <title>ETS Tables</title> <p>This section contains information about all the ETS tables in - the system. The following fields are interesting for each table:</p> + the system. The following fields are of interest for each table:</p> + <taglist> <tag><em>=ets:<owner></em></tag> - <item>Heading, states the owner of the table (a process identifier)</item> + <item> + <p>Heading. States the table owner (a process identifier).</p> + </item> <tag><em>Table</em></tag> - <item>The identifier for the table. If the table is a - <c><![CDATA[named_table]]></c>, this is the name.</item> + <item> + <p>The identifier for the table. If the table is a + <c><![CDATA[named_table]]></c>, this is the name.</p> + </item> <tag><em>Name</em></tag> - <item>The name of the table, regardless of whether it is a - <c><![CDATA[named_table]]></c> or not.</item> + <item> + <p>The table name, regardless of if it is a + <c><![CDATA[named_table]]></c> or not.</p> + </item> <tag><em>Hash table, Buckets</em></tag> - <item>This occurs if the table is a hash table, i.e. if it is not an - <c><![CDATA[ordered_set]]></c>.</item> + <item> + <p>If the table is a hash table, that is, if it is not an + <c><![CDATA[ordered_set]]></c>.</p> + </item> <tag><em>Hash table, Chain Length</em></tag> - <item>Only applicable for hash tables. Contains statistics about the - hash table, such as the max, min and avg chain length. Having a max much - larger than the avg, and a std dev much larger that - the expected std dev is a sign that the hashing of the terms is - behaving badly for some reason.</item> + <item> + <p>If the table is a hash table. Contains statistics about the + table, such as the maximum, minimum, and average chain length. + Having a maximum much larger than the average, and a standard + deviation much larger than the expected standard deviation is + a sign that the hashing of the terms + behaves badly for some reason.</p> + </item> <tag><em>Ordered set (AVL tree), Elements</em></tag> - <item>This occurs only if the table is an <c><![CDATA[ordered_set]]></c>. (The - number of elements is the same as the number of objects in the - table.)</item> + <item> + <p>If the table is an <c><![CDATA[ordered_set]]></c>. (The + number of elements is the same as the number of objects in the + table.)</p> + </item> <tag><em>Fixed</em></tag> - <item>If the table is fixed using ets:safe_fixtable or some internal - mechanism.</item> + <item> + <p>If the table is fixed using + <seealso marker="stdlib:ets#safe_fixtable/2"> + <c>ets:safe_fixtable/2</c></seealso> or some internal mechanism.</p> + </item> <tag><em>Objects</em></tag> - <item>The number of objects in the table</item> + <item> + <p>The number of objects in the table.</p> + </item> <tag><em>Words</em></tag> - <item>The number of words (usually 4 bytes/word) allocated to data - in the table.</item> + <item> + <p>The number of words (usually 4 bytes/word) allocated to data + in the table.</p> + </item> <tag><em>Type</em></tag> - <item>The type of the table, i.e. <c>set</c>, <c>bag</c>, - <c>dublicate_bag</c> or <c>ordered_set</c>.</item> + <item> + <p>The table type, that is, <c>set</c>, <c>bag</c>, + <c>dublicate_bag</c>, or <c>ordered_set</c>.</p> + </item> <tag><em>Compressed</em></tag> - <item>If this table was compressed.</item> + <item> + <p>If the table was compressed.</p> + </item> <tag><em>Protection</em></tag> - <item>The protection of this table.</item> + <item> + <p>The protection of the table.</p> + </item> <tag><em>Write Concurrency</em></tag> - <item>If write_concurrency was enabled for this table.</item> + <item> + <p>If <c>write_concurrency</c> was enabled for the table.</p> + </item> <tag><em>Read Concurrency</em></tag> - <item>If read_concurrency was enabled for this table.</item> + <item> + <p>If <c>read_concurrency</c> was enabled for the table.</p> + </item> </taglist> </section> @@ -435,167 +563,252 @@ <title>Timers</title> <p>This section contains information about all the timers started with the BIFs <c><![CDATA[erlang:start_timer/3]]></c> and - <c><![CDATA[erlang:send_after/3]]></c>. The following fields exists for each - timer:</p> + <c><![CDATA[erlang:send_after/3]]></c>. The following fields exist + for each timer:</p> + <taglist> <tag><em>=timer:<owner></em></tag> - <item>Heading, states the owner of the timer (a process identifier) - i.e. the process to receive the message when the timer - expires.</item> + <item> + <p>Heading. States the timer owner (a process identifier), + that is, the process to receive the message when the timer + expires.</p> + </item> <tag><em>Message</em></tag> - <item>The message to be sent.</item> + <item> + <p>The message to be sent.</p> + </item> <tag><em>Time left</em></tag> - <item>Number of milliseconds left until the message would have been - sent.</item> + <item> + <p>Number of milliseconds left until the message would have been + sent.</p> + </item> </taglist> </section> <section> <marker id="distribution_info"></marker> - <title>Distribution information</title> - <p>If the Erlang node was alive, i.e., set up for communicating + <title>Distribution Information</title> + <p>If the Erlang node was alive, that is, set up for communicating with other nodes, this section lists the connections that were active. The following fields can exist:</p> + <taglist> <tag><em>=node:<node_name></em></tag> - <item>The name of the node</item> + <item> + <p>The node name.</p> + </item> <tag><em>no_distribution</em></tag> - <item>This will only occur if the node was not distributed.</item> + <item> + <p>If the node was not distributed.</p> + </item> <tag><em>=visible_node:<channel></em></tag> - <item>Heading for a visible nodes, i.e. an alive node with a - connection to the node that crashed. States the channel number - for the node.</item> + <item> + <p>Heading for a visible node, that is, an alive node with a + connection to the node that crashed. States the channel number + for the node.</p> + </item> <tag><em>=hidden_node:<channel></em></tag> - <item>Heading for a hidden node. A hidden node is the same as a - visible node, except that it is started with the "-hidden" - flag. States the channel number for the node.</item> + <item> + <p>Heading for a hidden node. A hidden node is the same as a + visible node, except that it is started with the <c>"-hidden"</c> + flag. States the channel number for the node.</p> + </item> <tag><em>=not_connected:<channel></em></tag> - <item>Heading for a node which is has been connected to the crashed - node earlier. References (i.e. process or port identifiers) - to the not connected node existed at the time of the crash. - exist. States the channel number for the node.</item> + <item> + <p>Heading for a node that was connected to the crashed + node earlier. References (that is, process or port identifiers) + to the not connected node existed at the time of the crash. + States the channel number for the node.</p> + </item> <tag><em>Name</em></tag> - <item>The name of the remote node.</item> + <item> + <p>The name of the remote node.</p> + </item> <tag><em>Controller</em></tag> - <item>The port which controls the communication with the remote node.</item> + <item> + <p>The port controlling communication with the remote node.</p> + </item> <tag><em>Creation</em></tag> - <item>An integer (1-3) which together with the node name identifies - a specific instance of the node.</item> - <tag><em>Remote monitoring: <local_proc> <remote_proc></em></tag> - <item>The local process was monitoring the remote process at the - time of the crash.</item> - <tag><em>Remotely monitored by: <local_proc> <remote_proc></em></tag> - <item>The remote process was monitoring the local process at the - time of the crash.</item> + <item> + <p>An integer (1-3) that together with the node name identifies + a specific instance of the node.</p> + </item> + <tag><em>Remote monitoring: <local_proc> <remote_proc></em> + </tag> + <item> + <p>The local process was monitoring the remote process at the + time of the crash.</p> + </item> + <tag><em>Remotely monitored by: <local_proc> + <remote_proc></em></tag> + <item> + <p>The remote process was monitoring the local process at the + time of the crash.</p> + </item> <tag><em>Remote link: <local_proc> <remote_proc></em></tag> - <item>A link existed between the local process and the remote - process at the time of the crash.</item> + <item> + <p>A link existed between the local process and the remote + process at the time of the crash.</p> + </item> </taglist> </section> <section> <marker id="loaded_modules"></marker> - <title>Loaded module information</title> - <p>This section contains information about all loaded modules. - First, the memory usage by loaded code is summarized. There is - one field for "Current code" which is code that is the current - latest version of the modules. There is also a field for "Old - code" which is code where there exists a newer version in the - system, but the old version is not yet purged. The memory usage - is in bytes.</p> - <p>All loaded modules are then listed. The following fields exist:</p> + <title>Loaded Module Information</title> + <p>This section contains information about all loaded modules.</p> + + <p>First, the memory use by the loaded code is summarized:</p> + + <taglist> + <tag><em>Current code</em></tag> + <item> + <p>Code that is the current latest version of the modules.</p> + </item> + <tag><em>Old code</em></tag> + <item> + <p>Code where there exists a newer version in the + system, but the old version is not yet purged.</p> + </item> + </taglist> + + <p>The memory use is in bytes.</p> + + <p>Then, all loaded modules are listed. The following fields exist:</p> + <taglist> <tag><em>=mod:<module_name></em></tag> - <item>Heading, and the name of the module.</item> + <item> + <p>Heading. States the module name.</p> + </item> <tag><em>Current size</em></tag> - <item>Memory usage for the loaded code in bytes</item> + <item> + <p>Memory use for the loaded code, in bytes.</p> + </item> <tag><em>Old size</em></tag> - <item>Memory usage for the old code, if any.</item> + <item> + <p>Memory use for the old code, if any.</p> + </item> <tag><em>Current attributes</em></tag> - <item>Module attributes for the current code. This field is decoded - when looked at by the Crashdump Viewer tool.</item> + <item> + <p>Module attributes for the current code. This field is decoded + when looked at by the Crashdump Viewer tool.</p> + </item> <tag><em>Old attributes</em></tag> - <item>Module attributes for the old code, if any. This field is - decoded when looked at by the Crashdump Viewer tool.</item> + <item> + <p>Module attributes for the old code, if any. This field is + decoded when looked at by the Crashdump Viewer tool.</p> + </item> <tag><em>Current compilation info</em></tag> - <item>Compilation information (options) for the current code. This - field is decoded when looked at by the Crashdump Viewer tool.</item> + <item> + <p>Compilation information (options) for the current code. This + field is decoded when looked at by the Crashdump Viewer tool.</p> + </item> <tag><em>Old compilation info</em></tag> - <item>Compilation information (options) for the old code, if - any. This field is decoded when looked at by the Crashdump - Viewer tool.</item> + <item> + <p>Compilation information (options) for the old code, if + any. This field is decoded when looked at by the Crashdump + Viewer tool.</p> + </item> </taglist> </section> <section> <marker id="funs"></marker> - <title>Fun information</title> - <p>In this section, all funs are listed. The following fields exist - for each fun:</p> + <title>Fun Information</title> + <p>This section lists all funs. The following fields exist for each fun:</p> + <taglist> <tag><em>=fun</em></tag> - <item>Heading</item> + <item> + <p>Heading.</p> + </item> <tag><em>Module</em></tag> - <item>The name of the module where the fun was defined.</item> + <item> + <p>The name of the module where the fun was defined.</p> + </item> <tag><em>Uniq, Index</em></tag> - <item>Identifiers</item> + <item> + <p>Identifiers.</p> + </item> <tag><em>Address</em></tag> - <item>The address of the fun's code.</item> + <item> + <p>The address of the fun's code.</p> + </item> <tag><em>Native_address</em></tag> - <item>The address of the fun's code when HiPE is enabled.</item> + <item> + <p>The address of the fun's code when HiPE is enabled.</p> + </item> <tag><em>Refc</em></tag> - <item>The number of references to the fun.</item> + <item> + <p>The number of references to the fun.</p> + </item> </taglist> </section> <section> <marker id="proc_data"></marker> <title>Process Data</title> - <p>For each process there will be at least one <em>=proc_stack</em> - and one <em>=proc_heap</em> tag followed by the raw memory + <p>For each process there is at least one <em>=proc_stack</em> + and one <em>=proc_heap</em> tag, followed by the raw memory information for the stack and heap of the process.</p> - <p>For each process there will also be a <em>=proc_messages</em> - tag if the process' message queue is non-empty and a - <em>=proc_dictionary</em> tag if the process' dictionary (the - <c><![CDATA[put/2]]></c> and <c><![CDATA[get/1]]></c> thing) is non-empty.</p> + + <p>For each process there is also a <em>=proc_messages</em> + tag if the process message queue is non-empty, and a + <em>=proc_dictionary</em> tag if the process dictionary (the + <c><![CDATA[put/2]]></c> and <c><![CDATA[get/1]]></c> thing) is + non-empty.</p> + <p>The raw memory information can be decoded by the Crashdump - Viewer tool. You will then be able to see the stack dump, the - message queue (if any) and the dictionary (if any).</p> + Viewer tool. You can then see the stack dump, the + message queue (if any), and the dictionary (if any).</p> + <p>The stack dump is a dump of the Erlang process stack. Most of - the live data (i.e., variables currently in use) are placed on - the stack; thus this can be quite interesting. One has to - "guess" what's what, but as the information is symbolic, - thorough reading of this information can be very useful. As an - example we can find the state variable of the Erlang primitive - loader on line <c><![CDATA[(5)]]></c> in the example below:</p> + the live data (that is, variables currently in use) are placed on + the stack; thus this can be interesting. One has to + "guess" what is what, but as the information is symbolic, + thorough reading of this information can be useful. As an + example, we can find the state variable of the Erlang primitive + loader online <c><![CDATA[(5)]]></c> and <c><![CDATA[(6)]]></c> + in the following example:</p> + <code type="none"><![CDATA[ (1) 3cac44 Return addr 0x13BF58 (<terminate process normally>) -(2) y(0) ["/view/siri_r10_dev/clearcase/otp/erts/lib/kernel/ebin","/view/siri_r10_dev/ -(3) clearcase/otp/erts/lib/stdlib/ebin"] +(2) y(0) ["/view/siri_r10_dev/clearcase/otp/erts/lib/kernel/ebin", +(3) "/view/siri_r10_dev/clearcase/otp/erts/lib/stdlib/ebin"] (4) y(1) <0.1.0> -(5) y(2) {state,[],none,#Fun<erl_prim_loader.6.7085890>,undefined,#Fun<erl_prim_loader.7.9000327>,#Fun<erl_prim_loader.8.116480692>,#Port<0.2>,infinity,#Fun<erl_prim_loader.9.10708760>} -(6) y(3) infinity ]]></code> +(5) y(2) {state,[],none,#Fun<erl_prim_loader.6.7085890>,undefined,#Fun<erl_prim_loader.7.9000327>, +(6) #Fun<erl_prim_loader.8.116480692>,#Port<0.2>,infinity,#Fun<erl_prim_loader.9.10708760>} +(7) y(3) infinity ]]></code> + <p>When interpreting the data for a process, it is helpful to know - that anonymous function objects (funs) are given a name - constructed from the name of the function in which they are - created, and a number (starting with 0) indicating the number of - that fun within that function.</p> + that anonymous function objects (funs) are given the following:</p> + + <list type="bulleted"> + <item>A name constructed from the name of the function in which they are + created + </item> + <item>A number (starting with 0) indicating the number of that fun within + that function + </item> + </list> </section> <section> <marker id="atoms"></marker> <title>Atoms</title> - <p>Now all the atoms in the system are written. This is only - interesting if one suspects that dynamic generation of atoms could + <p>This section presents all the atoms in the system. This is only + of interest if one suspects that dynamic generation of atoms can be a problem, otherwise this section can be ignored.</p> - <p>Note that the last created atom is printed first.</p> + + <p>Notice that the last created atom is shown first.</p> </section> <section> <title>Disclaimer</title> - <p>The format of the crash dump evolves between releases of - OTP. Some information here may not apply to your - version. A description as this will never be complete; it is meant as + <p>The format of the crash dump evolves between OTP releases. + Some information described here may not apply to your + version. A description like this will never be complete; it is meant as an explanation of the crash dump in general and as a help when trying to find application errors, not as a complete specification.</p> |