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authorSiri Hansen <[email protected]>2011-08-29 15:58:45 +0200
committerSiri Hansen <[email protected]>2011-08-30 09:51:35 +0200
commit7ee8080d1127b30c935dfd896a8e78b3a34ee176 (patch)
treef02552d2d2d311dfd250bd28faf731ba6cdfc410 /lib/sasl/doc/src/release_handler.xml
parent9a52e239698ae62cddbc0d780502c72458867b6f (diff)
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Improve performance of upgrade when many processes have old code
This commit utilizes the new bif erlang:check_old_code/1 to check if a module has old code in the system or not before running erlang:check_process_code/2. This is to optimize release_handler:install_release (and release_handler:check_install_release). A new test is added which checks that after traversing all processes/modules once and purging all old code, the second run through this part of the code is "sufficiently" much faster. A note is also added in the reference manual for release_handler:install_release about how to go around the efficiency problem of this function.
Diffstat (limited to 'lib/sasl/doc/src/release_handler.xml')
-rw-r--r--lib/sasl/doc/src/release_handler.xml22
1 files changed, 21 insertions, 1 deletions
diff --git a/lib/sasl/doc/src/release_handler.xml b/lib/sasl/doc/src/release_handler.xml
index 4a973bc5ed..2781412848 100644
--- a/lib/sasl/doc/src/release_handler.xml
+++ b/lib/sasl/doc/src/release_handler.xml
@@ -4,7 +4,7 @@
<erlref>
<header>
<copyright>
- <year>1996</year><year>2009</year>
+ <year>1996</year><year>2011</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
@@ -299,6 +299,26 @@ release_handler:set_unpacked(RelFile, [{myapp,"1.0","/home/user"},...]).
<c>{update_paths,true}</c>, afterwards
<c>code:lib_dir(myapp)</c> will return
<c>/home/user/myapp-1.0</c>.</p>
+ <note>
+ <p>Before a new release is installed, the
+ <c>release_handler</c> checks that no processes have
+ references to old code of any of the modules that are to be
+ loaded. This operation can be very time consuming,
+ especially if there are many processes in the system, since
+ it might cause garbage collections and copying of data.</p>
+ <p>If it is desirable to reduce the time spent in this
+ function, then <seealso
+ marker="#check_install_release/1">check_install_release/1</seealso>
+ might be called first. This function does the same check for
+ old code, including garbage collection, and can be done in
+ the background before actually starting the upgrade by
+ calling <c>install_release</c>.</p>
+ <p>Code might even be purged (using
+ <c>code:purge/1</c>) after
+ <c>check_install_release</c> in order to completely
+ avoid the check for old code during
+ <c>install_release</c>.</p>
+ </note>
</desc>
</func>
<func>