# JVM -Xss tuning, isn't the default JVM value good enough? **URL:** \ **Category:** Elasticsearch\ **Created:** [November 27, 2012, 10:02am UTC](https://discuss.elastic.co/t/jvm-xss-tuning-isnt-the-default-jvm-value-good-enough/9840 "2012-11-27T10:02:29Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Lukas\_Vlcek1](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/lukas_vlcek1/32/819_2.png) [@Lukas\_Vlcek1](https://discuss.elastic.co/u/Lukas_Vlcek1)\ **Post date:** [November 27, 2012, 10:02am UTC](https://discuss.elastic.co/t/jvm-xss-tuning-isnt-the-default-jvm-value-good-enough/9840/1 "2012-11-27T10:02:29Z")
Hi, What is the motivation to specifically setup Xss JVM parameter in elasticsearch startup script? It seems that during the time the Xss went from 128k [1] up to 256k [2]. Is it that the default JVM value was causing troubles in some environments? Consuming way too much memory per thread or something like that? On the other hand this can hit ["The stack size specified is too small"] anybody who upgrades JVM without upgrading ES. Regards, Lukas [1] > [2] > -- ---
**Author:** ![jprante](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jprante/32/44941_2.png) [@jprante](https://discuss.elastic.co/u/jprante)\ **Post date:** [November 27, 2012, 6:10pm UTC](https://discuss.elastic.co/t/jvm-xss-tuning-isnt-the-default-jvm-value-good-enough/9840/2 "2012-11-27T18:10:57Z")
Hi Lukas\*,\* see [JDK 7 requires minimum of 256k stack size, update scripts to set it · Issue #1892 · elastic/elasticsearch · GitHub](https://github.com/elasticsearch/elasticsearch/issues/1892) and also [[CASSANDRA-4457] Find the cause for the need for a larger stack size with jdk 7 - ASF JIRA](https://issues.apache.org/jira/browse/CASSANDRA-4457) Elasticsearch starts with quite a bundle of thread pools, and there is also netty using some threads, so IMHO everything should be tried to reduce waste of memory, and thread stack size is one candidate. If it is known how much memory the stack frames the threads will allocate at most, you can assume it is safe to decrease the stack size limit under certain additional assumptions. The challenge is to find a good value, because the stack space consumption is not really comparable over different CPU architectures and operating systems. There is a vendor builtin stack size default in the stock JVM that depends on the CPU architecture and the operating system. But are they really suitable under all conditions? E.g. Solaris Sparc 64bit has a JVM Xss default of 512k because of the larger address pointers, and Solaris x86 has 320k. Linux has lower limits down to 256k. Windows 32bit with Java 6 has a default of 320k and Windows 64bit even 1024m stack space. Regards, Jörg On Tuesday, November 27, 2012 11:02:54 AM UTC+1, Lukáš Vlček wrote: > Hi, > > What is the motivation to specifically setup Xss JVM parameter in > elasticsearch startup script? It seems that during the time the Xss went > from 128k [1] up to 256k [2]. > > Is it that the default JVM value was causing troubles in some > environments? Consuming way too much memory per thread or something like > that? > > On the other hand this can hit ["The stack size specified is too small"] anybody > who upgrades JVM without upgrading ES. > > Regards, > Lukas > > [1] > [change default jvm tuning options · elastic/elasticsearch@ac27b45 · GitHub](https://github.com/elasticsearch/elasticsearch/commit/ac27b45524601207cdc56fc91a054d9661d8d20b) > [2] > [JDK 7 requires minimum of 256k stack size, update scripts to set it, … · elastic/elasticsearch@c56218a · GitHub](https://github.com/elasticsearch/elasticsearch/commit/c56218a41fe547574ad7357751e4d95c82a79aca) -- ---
**Author:** ![Lukas\_Vlcek1](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/lukas_vlcek1/32/819_2.png) [@Lukas\_Vlcek1](https://discuss.elastic.co/u/Lukas_Vlcek1)\ **Post date:** [November 27, 2012, 11:24pm UTC](https://discuss.elastic.co/t/jvm-xss-tuning-isnt-the-default-jvm-value-good-enough/9840/3 "2012-11-27T23:24:42Z")
Hi Jörg, thanks for detailed info. That is also my understanding of the situation. On the other I was trying to point out that if you are running older ES (like 0.18.x which comes with lower Xss value) and JVM is upgraded then ES might suddenly not start complaining about the stack size being too small. And this does not apply only to JDK7. Fortunately, changes like that between JVM versions are probably quite rare. Regards, Lukas On Tue, Nov 27, 2012 at 7:10 PM, Jörg Prante [joergprante@gmail.com](mailto:joergprante@gmail.com) wrote: > Hi Lukas\*,\* > > see [JDK 7 requires minimum of 256k stack size, update scripts to set it · Issue #1892 · elastic/elasticsearch · GitHub](https://github.com/elasticsearch/elasticsearch/issues/1892) > > and also [[CASSANDRA-4457] Find the cause for the need for a larger stack size with jdk 7 - ASF JIRA](https://issues.apache.org/jira/browse/CASSANDRA-4457) > > Elasticsearch starts with quite a bundle of thread pools, and there is > also netty using some threads, so IMHO everything should be tried to reduce > waste of memory, and thread stack size is one candidate. > > If it is known how much memory the stack frames the threads will allocate > at most, you can assume it is safe to decrease the stack size limit under > certain additional assumptions. > > The challenge is to find a good value, because the stack space consumption > is not really comparable over different CPU architectures and operating > systems. There is a vendor builtin stack size default in the stock JVM that > depends on the CPU architecture and the operating system. But are they > really suitable under all conditions? E.g. Solaris Sparc 64bit has a JVM > Xss default of 512k because of the larger address pointers, and Solaris x86 > has 320k. Linux has lower limits down to 256k. Windows 32bit with Java 6 > has a default of 320k and Windows 64bit even 1024m stack space. > > Regards, > > Jörg > > On Tuesday, November 27, 2012 11:02:54 AM UTC+1, Lukáš Vlček wrote: > > > Hi, > > > > What is the motivation to specifically setup Xss JVM parameter in > > elasticsearch startup script? It seems that during the time the Xss went > > from 128k [1] up to 256k [2]. > > > > Is it that the default JVM value was causing troubles in some > > environments? Consuming way too much memory per thread or something like > > that? > > > > On the other hand this can hit ["The stack size specified is too small"] anybody > > who upgrades JVM without upgrading ES. > > > > Regards, > > Lukas > > > > [1] [https://github.com/\*\*elasticsearch/elasticsearch/\*\*commit/](https://github.com/ **elasticsearch/elasticsearch/** commit/)\*\* > > ac27b45524601207cdc56fc91a054d**9661d8d20b[https://github.com/elasticsearch/elasticsearch/commit/ac27b45524601207cdc56fc91a054d9661d8d20b](https://github.com/elasticsearch/elasticsearch/commit/ac27b45524601207cdc56fc91a054d9661d8d20b) > > [2] [https://github.com/\*\*elasticsearch/elasticsearch/\*\*commit/](https://github.com/ **elasticsearch/elasticsearch/** commit/)** > > c56218a41fe547574ad7357751e4d9\*\*5c82a79aca[https://github.com/elasticsearch/elasticsearch/commit/c56218a41fe547574ad7357751e4d95c82a79aca](https://github.com/elasticsearch/elasticsearch/commit/c56218a41fe547574ad7357751e4d95c82a79aca) > > -- -- ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 3:02am UTC](https://discuss.elastic.co/t/jvm-xss-tuning-isnt-the-default-jvm-value-good-enough/9840/4 "2017-07-06T03:02:33Z")