Examine whether -Xrs flag to JVM could be used to improve our signal-handling
logic
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Key: JRUBY-2608
URL: http://jira.codehaus.org/browse/JRUBY-2608
Project: JRuby
Issue Type: Improvement
Reporter: Charles Oliver Nutter
Assignee: Thomas E Enebo
Fix For: JRuby 1.1.3
The -Xrs flag turns off the JVM's use of signal handlers that might otherwise
be used for Ruby programs in JRuby. It could be useful for us. From the docs:
{noformat}
-Xrs
Reduces use of operating-system signals by the Java virtual machine (JVM).
In a previous release, the Shutdown Hooks facility was added to allow
orderly shutdown of a Java application. The intent was to allow user cleanup
code (such as closing database
connections) to run at shutdown, even if the JVM terminates abruptly.
Sun's JVM catches signals to implement shutdown hooks for abnormal JVM
termination. The JVM uses SIGHUP, SIGINT, and SIGTERM to initiate the running
of shutdown hooks.
The JVM uses a similar mechanism to implement the pre-1.2 feature of
dumping thread stacks for debugging purposes. Sun's JVM uses SIGQUIT to perform
thread dumps.
Applications embedding the JVM frequently need to trap signals like SIGINT
or SIGTERM, which can lead to interference with the JVM's own signal handlers.
The -Xrs
command-line option is available to address this issue. When -Xrs is used on
Sun's JVM, the signal masks for SIGINT, SIGTERM, SIGHUP, and SIGQUIT are not
changed by the
JVM, and signal handlers for these signals are not installed.
There are two consequences of specifying -Xrs:
* SIGQUIT thread dumps are not available.
* User code is responsible for causing shutdown hooks to run, for
example by calling System.exit() when the JVM is to be terminated.
{noformat}
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