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User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.3.1)
Description of problem:
we are running an IM-type(instant messaging) server in a single process.
It was running fine on Redhat 9 with Sun java. After we upgraded to
redhat enterprise 3, we tried to use IBM java, but it hangs in a few
hours. Normal "kill" cannot kill the process, and we have to use "kill
-9". We gave up on IBM java and the info below refers to Sun java.
Then we switched back to Sun Java which was used redhat9. The problem
now is excessive memory usage.
the java process's memory usage grows every day, now already over 1G
bytes.(in a week or so)
and it has not broken yet, but at some point it will.
This was not the case on redhat 9, and the memory usage was under 100M.
The system now is:
Linux 2.4.21-4.ELsmp #1 SMP i686 i686 i386 GNU/Linux
We tried 2 java versions, and both have the same memory issue.
java version "1.4.1_01"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1_01-b01)
Java HotSpot(TM) Server VM (build 1.4.1_01-b01, mixed mode)
java version "1.4.2_03"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_03-b02)
Java HotSpot(TM) Server VM (build 1.4.2_03-b02, mixed mode)
$JAVA -server -showversion
We want to downgrade to redhat 9. Is it possible to install redhat 9
kernel RPM on enterprise 3? Or change some config so that enterprise 3
uses redhat 9 kernel/library
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Run a java server with a lot of thread creation and destrction.
Actual Results: java process keeps using more and more memory.
Expected Results: java process memory usage stablizes.
Because of this issue, we stopped our process of upgrading more redhat9
servers to Enterprise 3.
We think the problem has something to do with threads. Our java
program creates and destroys threads constantly, but at any given
time, there are less than 20 threads. Once we disable thread creation,
the memory usage stablizes.
Our guess is there is memory leak in the new thread library. Although
the java process uses more and more memory, the memory usage reported by
is very stable, under 70M.
I found out this is a bug in java 1.4.
more from this page:
set environment variable LD_ASSUME_KERNEL=2.4.1, this will disable
avoid the memory leak.
The errorid points to os_linux_i486.cpp, 774; further investigation shows
that a pthread_getattr_np() call just failed with ENOMEM. JVM relies on
pthread_getattr_np(), so it has no choice but to abort if the call fails.
Starting from Redhat AS-3 (NPTL-0.60 and later), pthread_getattr_np() will
allocate memory through malloc(), the memory is freed by
In JVM, we didn't call pthread_attr_destroy() after
causes a small memory leak whenever pthread_getattr_np() is called (it is
called during thread creation).
In a long running application, especially when it has created lots of
threads, the memory leaks could add up and cause an out-of-memory error.
A temporary workaround is to disable NPTL by setting LD_ASSUME_KERNEL to
Fix is to call pthread_attr_destroy() after pthread_getattr_np(). It has
been verified with 1.4.2_02 JDK.
Also I've been told that the issue has been fixed on the libc side too. It
will be available in the first update RHEL3 U1.
Fixed in RHEL3 U2. Closing.