[JBoss JIRA] Created: (JBTM-555) make memory leak tests more robust
by Jonathan Halliday (JIRA)
make memory leak tests more robust
Project: JBoss Transaction Manager
Issue Type: Task
Security Level: Public (Everyone can see)
Components: Testing, Transaction Core
Affects Versions: 4.6.1
Reporter: Jonathan Halliday
Assignee: Jonathan Halliday
Fix For: future
Some tests in the txcore group attempt to detect memory leaks by
take memory reading
take another memory reading
This is unreliable, as System.gc() is only advisory to the runtime. There is no way to FORCE gc from within the jvm. This causes the tests to be somewhat unreliable.
Dirty tricks to work around this include running the tests with a small heap (-Xmx5m). With less free space to work with, the gc tries harder. On a default size heap it mostly ignores System.gc(). Unfortunately the test framework does not make it easy to set -Xmx on a per test / test group basis.
Similar effect could perhaps be achieved by allocating all except a small portion of the available heap from within the vm using eg. new byte.
There is also the jvmti ForceGarbageCollection method, but that would require us to have a chunk of C code on each test platform, which is a pain.
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