Thanx for the reply As far as I know if thread space provided insufficient for JVM it should throw stack overflow exception is'nt ?? Ok Will this approach works: say I reduced stack size to 128 K Then I invoked every possible feature of my web app to see whether any of my modules are failing bcoz of reduced stack space. If every part of my app works fine I will commit on my current setting for -Xss If something fails, I will increase it and again run the test
but my one concern is, whether all this effort will yeld me any improvement or not? regards Srikanth On 7/27/05, Arup Vidyerthy <[EMAIL PROTECTED]> wrote: > On Windows I believe it is 256K. Don't reduce it to 128K unless you are > absolutely sure what you are doing. > > Also, sometimes when the JVM does run it trouble allocating stack correctly, > it may throw an exception (actually it may be an OutOfMemoryError) 'can't > create new native thread'.... It happened to us in our application when we > used the -Xss parameter to override the default stack size to 128K. > > Regards... > Arup Vidyerthy > > > -----Original Message----- > From: Darryl L. Miles [mailto:[EMAIL PROTECTED] > Sent: 27 July 2005 12:03 > To: Tomcat Users List > Subject: Re: setting -Xss option and its impact on servlet threads > > > Peddireddy Srikanth wrote: > > > 1) what is the default stack size for Sun JVM on windows (Win 2003 to > >be more specefic)?? > > > > > Dont know. > > > 2) Will this setting affect both normal threads and the servlet > >threads created by tomcat?? or only normal threads? > > > > > I believe there is a 1:1 corelation between all Java application threads, be > they Servlet or normal threads. That is to say a Servlet thread uses > exactly 1 Java thread. > > > 3) If I set that to, say 128K , and if some of my thread (servlet or > >normal) needed more stack space than this in any case what happens > >(obvious answer for this would be that thread execution would fail but > >I want to know it from some one who experienced it) > > > > > Are you able to change the stack size on a per Java Thread basis? > > If the underlying JVM uses kernel level threads and stack arrangement in a > 1:1 fashion (unlikely from the observations I've seen), an unmapped > page/area is usualy left at the end of the stack space if this is touched > (read or write) the application will get a terminal signal and the entire > JVM forced to exit just like it would accessing any other bit of invalid > memory. > > However as JVM is a sandbox and it can know the amount of stack space a > method needs before its invoked it is completely possible for it to be able > to check/test its virtual Java stack has enough space left in the CPU > instruction stack as there does not need to be 1:1 to the Java execution > stack. Its possible for a JVM to implement its Java code execution stack > completely within the operating system heap area. > > I dont believe Java in general needs a large java execution stack as all > arrays are implemented as object allocations that come from the heap. > So its not like the C language where you can have a few Kb byte array on a > whim, in Java it just has to store the pointers to that array as a local > variable in the java execution stack. > > > I would be very interested to understand how Sun's JVM application stack > works and its interactions with OS level threads, stacks and address space > applications. > > With platform level threads there is a clear trade off with thread stack > size and number of available threads, amount of available heap and number of > library / file mappings (when working with 32bit CPUs at least). They all > squeeze each other for their bit of address space but in Java this does not > seem to be the case so much. > > -- > Darryl L. Miles > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > > > ___________________________________________________________ > How much free photo storage do you get? Store your holiday > snaps for FREE with Yahoo! Photos http://uk.photos.yahoo.com > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
