JVM Options
Hello all:
The CPU on the windows machine of this sun java system web server 6.1 sp6 was runing 100%. It has 4 cpus and 4gb memory. The webserver performance came to a halt. It did not accept any new connections and was extremely slow.
The current jvm setting is -Xmx256m. I am following the doc and trying to setup the jvm profiler. I added the jvm option "thread=y, depth=3" in the jvm profiler page. I also added the same option "thread=y, depth=3" in Jvm options page. I then restarted the web server. It created the log.txt file in config directory. I did nothing in server.xml file.
questions are:
1) What is the best way to see where is the bottleneck? Is JVM profiling only way to go? What is the process to identify why the cpu is 100%
2) Where would the jvm profile information store at? After logging in the website I tried to see if log.txt has any information. It has no info.
Thanks in advance for any help!
the current log.txt is..
<code>
JAVA PROFILE 1.0.1, created Wed Mar 21 15:29:20 2007
Header for -agentlib:hprof (or -Xrunhprof) ASCII Output (J2SE 1.5 JVMTI based)
@(#)jvm.hprof.txt1.3 04/02/09
Copyright (c) 2004 Sun Microsystems, Inc. All Rights Reserved.
WARNING! This file format is under development, and is subject to
change without notice.
This file contains the following types of records:
THREAD START
THREAD ENDmark the lifetime of Java threads
TRACErepresents a Java stack trace. Each trace consists
of a series of stack frames. Other records refer to
TRACEs to identify (1) where object allocations have
taken place, (2) the frames in which GC roots were
found, and (3) frequently executed methods.
HEAP DUMPis a complete snapshot of all live objects in the Java
heap. Following distinctions are made:
ROOTroot set as determined by GC
CLSclasses
OBJinstances
ARRarrays
SITESis a sorted list of allocation sites. This identifies
the most heavily allocated object types, and the TRACE
at which those allocations occurred.
CPU SAMPLESis a statistical profile of program execution. The VM
periodically samples all running threads, and assigns
a quantum to active TRACEs in those threads. Entries
in this record are TRACEs ranked by the percentage of
total quanta they consumed; top-ranked TRACEs are
typically hot spots in the program.
CPU TIMEis a profile of program execution obtained by measuring
the time spent in individual methods (excluding the time
spent in callees), as well as by counting the number of
times each method is called. Entries in this record are
TRACEs ranked by the percentage of total CPU time. The
"count" field indicates the number of times each TRACE
is invoked.
MONITOR TIMEis a profile of monitor contention obtained by measuring
the time spent by a thread waiting to enter a monitor.
Entries in this record are TRACEs ranked by the percentage
of total monitor contention time and a brief description
of the monitor. The "count" field indicates the number of
times the monitor was contended at that TRACE.
MONITOR DUMPis a complete snapshot of all the monitors and threads in
the System.
HEAP DUMP, SITES, CPU SAMPLES|TIME and MONITOR DUMP|TIME records are generated
at program exit. They can also be obtained during program execution by typing
Ctrl-\ (on Solaris) or by typing Ctrl-Break (on Win32).
--
</code>
