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authorErlang/OTP <[email protected]>2009-11-20 14:54:40 +0000
committerErlang/OTP <[email protected]>2009-11-20 14:54:40 +0000
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The R13B03 release.OTP_R13B03
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+
+
+
+ Help for the application monitor system
+ ---------------------------------------
+
+
+
+
+
+ The monitor system has two types of windows, the node window
+ which opens when appmon:start() is evaluated, and the
+ application window which opens when an application in the node
+ window is clicked on.
+
+ All nodes that are known to appmon is shown in the node
+ window, normally this is all Erlang nodes visible with the
+ nodes() command.
+
+
+The Node window
+---------------
+
+ The node window monitors nodes. At the top there is a menubar
+ and below that, each known node is shown separated with a thin
+ line from the others. A node is represented by its name as
+ root of its application tree. The node name pictures the
+ application controller on that node. The name itself is a menu
+ where operations on the node can be performed (rebooting it
+ for instance). To the far left is a load meter (like those on
+ a tape deck) which measures the current load at the
+ node. Below the node name (the application controller) is a
+ tree with applications, clicking on these applications starts
+ the application monitor.
+
+
+ The top window menubar
+ ----------------------
+
+ File:Quit - Stop the monitor.
+
+ Options:
+ Load: time - Load is calculated (roughly) as processor time.
+ Load: queue - Load is calculated as the length of the ready
+ queue.
+ Load: prog - A progressive scale is used for load values.
+ Load: linear - A linear scale is used for load values.
+
+ Help - Prints this message.
+
+
+ The application controller menu
+ -------------------------------
+ Reboot - Reboot the node
+ Restart - Restart the node
+ Stop - Stop the node
+
+
+ The load meter
+ --------------
+
+ Load can be measured as processor time / elapsed time or as
+ the length of the runtime queue, depending on the setting in
+ the Options menu.
+
+
+The Application window
+----------------------
+
+ The application window monitors an application. It will
+ automaticly update the window every other second or so if
+ there are any changes in the process tree. At the top there is
+ a menubar followed by a toolbar and then the application
+ tree. Application trees come in two flavours: supervision
+ view, where a strict supervision tree is shown, and process
+ view, where all linked processes in the application is shown.
+
+
+ The application window menubar
+ ------------------------------
+
+ File:Quit - Quit the application window.
+
+ Options:Refresh - Update process information and refresh
+ screen.
+
+ Options:Sup. view
+ - Show strict supervision tree only.
+
+ Options:Proc. view
+ - Show all linked processes.
+
+ Help - Prints this message.
+
+
+ The application window toolbar
+ ------------------------------
+
+ The application toolbar controls the actions of the mouse
+ pointer. Clicking on a process in the application window have
+ different meaning depending on which tool is selected. The
+ procedure is to first press a button (T for trace for example)
+ and then click on the process that should be traced.
+
+ Info - Process information is printed in the shell. This mode
+ is default and automaticly returned to after a mouse click.
+
+ Send - Send a message to the clicked process. A window will
+ pop up where the message can be written (and you can also
+ change the destination pid). Double clicking on this button
+ pops up a window where pid and message can be filled in.
+
+ Trace - Toggle trace on/off on the process. Note that not all
+ processes respond to the sys:trace call.
+
+ Kill - Send a non-trappable exit signal to the process.
+
+
+Technical Detail
+----------------
+
+ Files and distribution
+ ----------------------
+
+ Appmon is a distributed program but all graphics is handled on
+ one node (the one it is started on) so GS need only to be
+ loaded on that single node. All real monitoring is done in a
+ single module (appmon_info) being run on each node which acts
+ as an information centre. The various windows (node and
+ application) then subscribe for information.
+
+ In summary: only the appmon_info module must be accessible by
+ the clients, the rest of the appmon files are only needed at
+ the server.
+
+ Trouble shooting
+ ----------------
+
+ Q. Why doesn't all my nodes show up in the node window?
+
+ A 1. Are the nodes visible with the nodes() command in the
+ shell? If not you must do net:ping(NodeName) to add nodes to
+ the Erlang distribution.
+
+ A 2. Is the appmin_info module loadable at the missing
+ node(s)?
+
+ Q. Why doesn't the application window show my application
+ supervision structure?
+
+ A. Does your application have a real application master? It is
+ absolutely necessary that your top process behaves as a
+ supervisor should (a program is not supervised just because it
+ is started with application:start).