Date: Tue, 06 Dec 2005 18:33:31 +0800 From: David Xu <davidxu@freebsd.org> To: Michael Vince <mv@roq.com> Cc: freebsd-threads@freebsd.org, performance@freebsd.org, freebsd-java@freebsd.org Subject: Re: More threads Message-ID: <439568FB.1000804@freebsd.org> In-Reply-To: <43956122.5020106@roq.com> References: <43956122.5020106@roq.com>
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Michael Vince wrote: > Hi All, > > I been benchmarking a Java servlet I have created and I want to be able > to handle a massive amount of simultaneous connections. > So far using benchmarking tools I have been able to get around 2,565 > threads on the Tomcat 5.5 Java process (with native 1.4.2 Java) > according to ps -auxwH | grep -c 'java' > > But I just can't seem to get past that mark, I have a lot of memory > currently the Tomcat is allocated 2gigs of memory. > > When I max it out with my benchmarks I get this in catalina Tomcat 5.5 > but there is still plenty of free memory to the Tomcat process. > SEVERE: Caught exception (java.lang.OutOfMemoryError: unable to create > new native thread) executing org.apache.jk.common.SocketAcceptor@f36e59, > terminatingthread > > I have been testing with my libmap.conf with these different types of > implementations. > > [/usr/local/jdk1.4.2/] > #libpthread.so libc_r.so > #libpthread.so.2 libc_r.so.6 > libpthread.so.2 libthr.so.2 > libpthread.so libthr.so > libc_r.so.6 libthr.so.2 > libc_r.so libthr.so > > I have been getting the best performance with libthr and have been using > the above libthr and with these settings below. > > I have set my max_threads in /etc/sysctl.conf to a massive amount. > > kern.threads.max_threads_per_proc=40000 > kern.threads.max_groups_per_proc=40000 > > ps -auxwH | grep -c 'java' > 2565 > > I am using Apache2.2 with the new built in AJP module which has been a > great addition to Apache 2.2. > I have been able to get the setup performing most stable (no 503 status > errors) but with less performance / threads with the libmap.conf below. > [/usr/local/jdk1.4.2/] > libpthread.so libc_r.so > libpthread.so.2 libc_r.so.6 > > I am on 6.0 Release i386, dual Intel P4, generic SMP kernel. > > With Tomcat on Windows XP I have been able to get it running better. > Does any one know of some other sysctls that increase the amount of > threads in libthr which I am assuming utilizes the above sysctls. Does > any one know how many threads can be created in Java on FreeBSD? > > Cheers, > Mike > Number of threads you can create if you use libthr is limited by following factors: 1) sysctl: kern.threads.max_threads_per_proc kern.threads.max_groups_per_proc 2) stack per-thread userland stack, default number on 64 bits platform is 2M, on 32 bits platform, it is 1M. I don't know whether java supports adjusting default per-thread stack size. if can not, we may add an environment variable to thread libraries, for example: LIBPTHREAD_THREAD_STACKSIZE allows user to set default stack size. Thread also needs a kernel mode stack when it is in kernel, if I am right, it is 16K bytes per-thread. if you create too many threads, make sure both side won't exhaust address space, and because kernel stack can not be swapped out when process is running, you'd make sure physical memory can not be exhausted. 3) check memory limits type limits command: Resource limits (current): cputime infinity secs filesize infinity kB datasize 524288 kB stacksize 65536 kB coredumpsize infinity kB memoryuse infinity kB memorylocked infinity kB maxprocesses 5547 openfiles 11095 sbsize infinity bytes vmemoryuse infinity kB if address space is not large enough, you have to reconfigure kernel to allow larger space. Fix me if I am wrong. David Xu
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