The web-application is based on a SingleThreadModel
servlet. It is accessed through Apache which uses
mod_jk to load-balance two Tomcats running the
web-application; versions are
Apache-1.3.27
Tomcat-4.1.24
Occasionally, numerous sockets in CLOSE_WAIT state get
built up between Apache and the Tomcats, and the
web-pages just stop opening up; the browser keeps on
waiting for the page to load. Analysing the Tomcat's
JVM thread-dumps reveals the following:
Tomcat-1
---------------
9 threads [ at
java.net.SocketInputStream.socketRead(Native Method)]
55 threads [at java.lang.Object.wait(Native Method)]
Tomcat-2
---------------
10 threads [ at
java.net.SocketInputStream.socketRead(Native Method)]
52 threads [at java.lang.Object.wait(Native Method)]
The detailed stack-traces for the above two types of
threads are given below:
3XMTHREADINFO "Thread-87" (TID:0x333777A0,
sys_thread_t:0x608A8AC0, state:R, native ID:0x537E)
prio=5
4XESTACKTRACE at
java.net.SocketInputStream.socketRead(Native Method)
4XESTACKTRACE at
java.net.SocketInputStream.read(SocketInputStream.java(Compiled
Code))
4XESTACKTRACE at
java.io.BufferedInputStream.fill(BufferedInputStream.java(Compiled
Code))
4XESTACKTRACE at
java.io.BufferedInputStream.read1(BufferedInputStream.java(Compiled
Code))
4XESTACKTRACE at
java.io.BufferedInputStream.read(BufferedInputStream.java(Compiled
Code))
4XESTACKTRACE at
org.apache.jk.common.ChannelSocket.read(ChannelSocket.java(Compiled
Code))
4XESTACKTRACE at
org.apache.jk.common.ChannelSocket.receive(ChannelSocket.java(Compiled
Code))
4XESTACKTRACE at
org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java(Compiled
Code))
4XESTACKTRACE at
org.apache.jk.common.SocketConnection.runIt(ChannelSocket.java(Compiled
Code))
4XESTACKTRACE at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:619)
4XESTACKTRACE at
java.lang.Thread.run(Thread.java(Compiled Code))
3XHNATIVESTACK Native Stack
NULL ------------
3XHSTACKLINE at 0xD0DB6918 in sysTimeout
3XHSTACKLINE at 0xD0BD94E8 in JVM_Timeout
3XHSTACKLINE at 0xD100BBBC in
Java_java_net_SocketInputStream_socketRead
... ...
3XMTHREADINFO "Thread-86" (TID:0x33377800,
sys_thread_t:0x608A56C0, state:CW, native ID:0x417D)
prio=5
4XESTACKTRACE at java.lang.Object.wait(Native
Method)
4XESTACKTRACE at
java.lang.Object.wait(Object.java(Compiled Code))
4XESTACKTRACE at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:595)
4XESTACKTRACE at
java.lang.Thread.run(Thread.java(Compiled Code))
3XHNATIVESTACK Native Stack
NULL ------------
3XHSTACKLINE at 0xD0011FCC in
_pthread_event_wait
3XHSTACKLINE at 0xD000DFD0 in _cond_wait_local
3XHSTACKLINE at 0xD000E43C in _cond_wait
3XHSTACKLINE at 0xD000F090 in
pthread_cond_wait
3XHSTACKLINE at 0xD0DB1934 in condvarWait
3XHSTACKLINE at 0xD0DB05F4 in sysMonitorWait
3XHSTACKLINE at 0xD0C74050 in lkMonitorWait
3XHSTACKLINE at 0xD0BE7C30 in JVM_MonitorWait
_________
Has anyone experienced such problems. Suggestions and
solutions are most welcome.
Thanks,
Gulen
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