From 7ee8080d1127b30c935dfd896a8e78b3a34ee176 Mon Sep 17 00:00:00 2001
From: Siri Hansen
Date: Mon, 29 Aug 2011 15:58:45 +0200
Subject: 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.
---
lib/sasl/doc/src/release_handler.xml | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
(limited to 'lib/sasl/doc/src/release_handler.xml')
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 @@
- 19962009
+ 19962011
Ericsson AB. All Rights Reserved.
@@ -299,6 +299,26 @@ release_handler:set_unpacked(RelFile, [{myapp,"1.0","/home/user"},...]).
{update_paths,true}, afterwards
code:lib_dir(myapp) will return
/home/user/myapp-1.0.
+
+ Before a new release is installed, the
+ release_handler 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.
+ If it is desirable to reduce the time spent in this
+ function, then check_install_release/1
+ 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 install_release.
+ Code might even be purged (using
+ code:purge/1) after
+ check_install_release in order to completely
+ avoid the check for old code during
+ install_release.
+
--
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