On 6 Mar 2012, at 08:16, "André Warnier" <a...@ice-sa.com> wrote:
> Pid wrote: >> On 06/03/2012 07:12, Rainer Frey wrote: >>> On 05.03.2012, at 14:14, Philippe ROUXEL wrote: >>> >>>>>> When I set JAVA_OPTS= -Xmx1024m -Xss75m >>>>> That means: each thread get a stack of 75MB. One of the following applies: >>>>> * the operating system has a limit on thread stack size >>>>> * the per process memory limit is reached before all initial tomcat >>>>> threads are started >>>>> * the system runs out of total memory before all initial tomcat threads >>>>> are started >>>>> >>>>> 75MB thread stack size seems quite insane, the default is around 1-2MB. >>>>> Perhaps you meant to set -Xms (which sets the initial Java heap size)? >>>> 75MB of stack is needed by hibenate to save the data aka a graph. >>> I haven't used hibernate personally, but I never heard anything like that. >>> So please elaborate. Where did you get that information? >>> Also what do you mean with "graph"? The graph of associated objects that >>> are updated by one hibernate call, or is your data actually graph data? >>> If so, how is that mapped? do you have any self-referential associations? >>> Is it really stack that you are talking about? >> I'm also interested in the answers to these questions. > > Ok, to get back to the OP's original question/assumption : > > Assuming that "-Xss75M" tells the JVM to allocate 75 MB of memory for the > stack of each new thread created by the JVM, and noting that for a typical > Tomcat instance, a minimum of about 10 threads seem to be created (with an > additional one for each request being processed), this setting of "-Xss75M" > would mean that a minimum of 750 MB is being allocated for the threads' stack. > > Assuming on the other hand that this is a 32-bit system and JVM (the OP > didn't really say, but was mentioning Windows XP), where the maximum > addressable memory for a process is 4 GB (of which 1 GB more or less are used > by the OS itself); and considering the setting of -Xmx1024M for the Heap; and > considering that the rest of the JVM and Tomcat may use some 1024 MB by > themselves (for other things than the Heap and thread stacks); > Considering all this thus, it is not really so surprising that the OP would > get an OOM error at some point. > > Noting on the other hand that the JVM stack should be mainly used to push and > pop subroutine/function parameters as they are being called, and that a > reasonable stack size seems to be around 512KB at most, this explains several > comments here which seem to put in doubt the wisdom of allocation 75 MB for > the stack of each Java thread. 75Mb is far too much for the thread stack size in a normal application. I am not certain that it is necessarily fully allocated, just to confuse matters further. I vaguely remember another discussion about this, but can't find it in the archives. p > I am far from a specialist, but considering that Hibernate seems to be some > kind of "generic" tool, it is a bit unlikely that using it would require to > set the stack size to an amount that is at least 150 times the JVM default, > no ? > > All this seems to point - as usual - to some application problem, with as > Chris pointed out some runaway recursive function call or similar. > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
