EAServer Performance Tuning Techniques

The HTTP thread settings allow you to balance memory resources. A maximum value set too high needlessly uses memory resources. To tune this setting, monitor the total number of hits listed in the httpstat.dat file for indications of a heavily loaded server, and adjust the maximum thread setting as necessary.

Setting this number too high will result in thrashing, with many threads waiting for a slice of CPU time. As a general guideline, consider a limit of 100 clients per CPU on Solaris, and 75 clients per CPU on Windows.

· com.sybase.jaguar.server.http.maxthreads
· com.sybase.jaguar.server.http.numthreads

Section 10 System-Level Tuning and Sizing

"HTTP Config" in EAServer System Administration Guide

Extra threads are needed for service components, thread manager and message service. If you are not calculating precisely, a guideline is to add another 50 threads.

Important Note: See component Bind Thread property -- components with this setting require twice as many threads.

Stack size determines how many client requests can be served simultaneously. If there are a large number of clients utilizing the server, you may want to reduce the default stack size, which is the amount of memory reserved for the call stack associated with each thread.

For Unix, set the stack size using the com.sybase.jaguar.server.stacksize property.
For NT you need to modify the jagsrv.exe using editbin.

You can specify the minimum and maximum JVM heap size with com.sybase.jaguar.server.jvm.maxHeapSize and com.sybase.jaguar.server.jvm.minHeapSize

(This property is valid for any version of the JVM)

"Repository Properties Reference" in EAServer System Administration Guide

Memory Management within Java Processes

NT & Solaris flags

• -Xms - minimum heap size
  Always increase the -Xms to a reasonable size (such as at least 64m) so the JVM does not have to spend time allocating memory.

   

• -Xmx - maximum heap size
  If you have the memory to spare, set -Xms to the same size as -Xmx.
  (Note: On Solaris, the maximum value for -Xmx is 4g. In order to use the maximum value on Solaris, check shmmax in /etc/system that
  shmsys:shminfo_shmmax=0xffffffff

   

• Garbage Collection (GC)
  These flags are for tuning the Garbage Collections memory allocations and are highly dependent on the behavior of your application. They should only be set after collecting statistics on the GC behavior of your application.

   

  • -XX:NewSize - minimum size of the young generation
    
  • -XX:MaxNewSize - maximum size of the young generation
    
  • -XX:NewRatio - ratio between young and old generation
    
  • -XX:SurvivorRatio - ratio of survivor space with respect to young generation, there are 2 survivor spaces in the young generation

     

  • Setting NewSize and MaxNewSize to each other bounds the size of the young generation like -Xms and -Xmx for the heap size. NewRatio is a more coarse level option to do the same thing. The SurvivorRatio is set to 25 by default and should be sufficient. You should set the NewSize and MaxNewSize to half the size of -Xmx if you observe a lot of regular GCs happening and want to delay a full GC as much as possible. Your application will run more smoothly for the majority of the time and you only pay for the one full GC instead of many GCS throughout your application.

     

  • -XX:ThreadStackSize
    If you know that EAServer will be creating a lot of threads, like when servicing a lot of clients or doing operations like creating a lot of objects or beans, then it might be of benefit to lower the stack size so that they don't take up a lot of heap. Try setting to 128k or 64k(min) to see if that will cause less GCS and help with performance.

Solaris-Only flags

• -XX:TLESize
  Size of the thread local portions of heap in young generation only in the server vm.

   

• -XX:-UseTLE
  Turn off thread local heaps.
  For the server vm, you could completely eliminate TLE or tune the size so that they don't impact heap space when there are many threads.

   

• -XX:+OverrideDefaultLibthread
• -XX:+UseLWPSynchronization
  
  • If you find that EAServer is causing a lot of context switches, or observe an abnormally high amount of %sys cpu usage on a multi-cpu Solaris machine when running EAServer, try using the alternative thread-library that comes with Solaris 2.8 and turning on the -XX:+OverrideDefaultLibthread

    In order to use the alternative thread library, follow these steps:

    1. add -XX:+OverrideDefaultLibthread to JVM options
    2. in shell: LD_LIBRARY_PATH=/usr/lib/lwp
       export LD_LIBRARY_PATH
    3. start EAServer

        

  • On Solaris 2.6, try using -XX:+UseLWPSynchronization to see if that helps as the alternative thread library is not available in 2.6

     

• -XX+UseISM
  Intimate Shared Memory (ISM). ISM provides the benefit of having larger pages(4mb) and locking pages to memory. If you have enough memory to dedicate to EAServer, then turning on ISM could help performance. Be aware that ISM does not guarantee larger pages unless your system has been rebooted and there is enough contiguous physical memory to fulfill ISM needs.

  Requirements in /etc/system
  

  • 2.8:
    · set shmsys:shminfo_shmmax=0xffffffff
    · set shmsys:shminfo_shmseg=32
    
  • 2.6:
    · set shmsys:shminfo_shmmax=0xffffffff
    · set shmsys:shminfo_shmseg=32
    · set enable_grp_ism=1

     

• -XX:-DisableExplicitGC
  Disable calls to explicit GC.
  

  EAServer calls System.gc() periodically. You can try disabling this to see if it will help GC performance. The System.gc called is just a hint, so turning on DisableExplicitGC might not do anything.

Allow Just-In-Time compiling (JIT) by setting the com.sybase.jaguar.server.jvm.nojit property to false. JIT converts Java bytecode into native machine code, which generally runs much faster than when the bytecode is executed by the interpreter.

"Repository Properties Reference" in EAServer System Administration Guide

Just-In-Time Compilers on Java Developer Connection

For improved performance, EAServer 4.0+ can run with JDK 1.3 and the Java HotSpot virtual machine. On some platforms, EAServer can also use the Java HotSpot VM with JDK 1.2.

"Creating and Configuring Servers" in EAServer System Administration Guide

Java HotSpot Performance Engine Architecture

Be sure all unnecessary tracing is off. This includes the server-level trace options for Attentions, Network Driver APIs, Network Driver Requests, Protocol Data, Protocol Headers, Servlets, JAAS Debug, JCM Trace.

EAServer 4.1+ supports caching of static content. Static page caching can increase performance by caching static files in memory. You can configure the cache size, which files are cached, and how long the cached content is stored.

• Cache Size
  The default cache size is 10 megabytes, which should be sufficient for most uses unless an application includes a lot of static images/texts.

   

• Cache timeout
  The default timeout is 10 minutes. Set this to a higher value when you know the static content being served does not change often.

   

• Exclusion List
  Exclude-files are useful for turning off things that you know are used sparingly to ensure the cache stays relevant. You wouldn't want to inadvertently bump off 100 cached images because a request came in for a 5mb PDF that is only used once. See:
  • com.sybase.jaguar.server.http.cache.exclude-files
  • com.sybase.jaguar.server.http.cache.webapps.exclude-files