Over a million developers have joined DZone.

Java HotSpot VM (Virtual Machine) Performance Tuning: Command-line options

DZone's Guide to

Java HotSpot VM (Virtual Machine) Performance Tuning: Command-line options

· Java Zone
Free Resource

What every Java engineer should know about microservices: Reactive Microservices Architecture.  Brought to you in partnership with Lightbend.

Option and Default Value Description
-XX:+AggressiveOpts Turn on point performance compiler optimizations that are expected to be default in upcoming releases. (Introduced in 5.0 update 6.)
-XX:CompileThreshold=10000 Number of method invocations/branches before compiling [-client: 1,500]
-XX:LargePageSizeInBytes=4m Sets the large page size used for the Java heap. (Introduced in 1.4.0 update 1.) [amd64: 2m.]
-XX:MaxHeapFreeRatio=70 Maximum percentage of heap free after GC to avoid shrinking.
-XX:MaxNewSize=size Maximum size of new generation (in bytes). Since 1.4, MaxNewSize is computed as a function of NewRatio. [1.3.1 Sparc: 32m; 1.3.1 x86: 2.5m.]
-XX:MaxPermSize=64m Size of the Permanent Generation.  [5.0 and newer: 64 bit VMs are scaled 30% larger; 1.4 amd64: 96m; 1.3.1 -client: 32m.]
-XX:MinHeapFreeRatio=40 Minimum percentage of heap free after GC to avoid expansion.
-XX:NewRatio=2 Ratio of new/old generation sizes. [Sparc -client: 8; x86 -server: 8; x86 -client: 12.]-client: 4 (1.3) 8 (1.3.1+), x86: 12]
-XX:NewSize=2.125m Default size of new generation (in bytes) [5.0 and newer: 64 bit VMs are scaled 30% larger; x86: 1m; x86, 5.0 and older: 640k]
-XX:ReservedCodeCacheSize=32m Reserved code cache size (in bytes) – maximum code cache size. [Solaris 64-bit, amd64, and -server x86: 48m; in 1.5.0_06 and earlier, Solaris 64-bit and and64: 1024m.]
-XX:SurvivorRatio=8 Ratio of eden/survivor space size [Solaris amd64: 6; Sparc in 1.3.1: 25; other Solaris platforms in 5.0 and earlier: 32]
-XX:TargetSurvivorRatio=50 Desired percentage of survivor space used after scavenge.
-XX:ThreadStackSize=512 Thread Stack Size (in Kbytes). (0 means use default stack size) [Sparc: 512; Solaris x86: 320 (was 256 prior in 5.0 and earlier); Sparc 64 bit: 1024; Linux amd64: 1024 (was 0 in 5.0 and earlier); all others 0.]
-XX:+UseBiasedLocking Enable biased locking. For more details, see thistuning example. (Introduced in 5.0 update 6.) [5.0: false]
-XX:+UseFastAccessorMethods Use optimized versions of Get<Primitive>Field.
-XX:-UseISM Use Intimate Shared Memory. [Not accepted for non-Solaris platforms.] For details, see Intimate Shared Memory.
-XX:+UseLargePages Use large page memory. (Introduced in 5.0 update 5.) For details, see Java Support for Large Memory Pages.
-XX:+UseMPSS Use Multiple Page Size Support w/4mb pages for the heap. Do not use with ISM as this replaces the need for ISM. (Introduced in 1.4.0 update 1, Relevant to Solaris 9 and newer.) [1.4.1 and earlier: false]
-XX:+UseStringCache Enables caching of commonly allocated strings.
-XX:AllocatePrefetchLines=1 Number of cache lines to load after the last object allocation using prefetch instructions generated in JIT compiled code. Default values are 1 if the last allocated object was an instance and 3 if it was an array.
-XX:AllocatePrefetchStyle=1 Generated code style for prefetch instructions.
0 – no prefetch instructions are generate*d*,
1 – execute prefetch instructions after each allocation,
2 – use TLAB allocation watermark pointer to gate when prefetch instructions are executed.
-XX:+UseCompressedStrings Use a byte[] for Strings which can be represented as pure ASCII. (Introduced in Java 6 Update 21 Performance Release)
-XX:+OptimizeStringConcat Optimize String concatenation operations where possible. (Introduced in Java 6 Update 20)


From http://singztechmusings.in/java-hotspot-vm-virtual-machine-performance-tuning-command-line-options/

Microservices for Java, explained. Revitalize your legacy systems (and your career) with Reactive Microservices Architecture, a free O'Reilly book. Brought to you in partnership with Lightbend.


Opinions expressed by DZone contributors are their own.


Dev Resources & Solutions Straight to Your Inbox

Thanks for subscribing!

Awesome! Check your inbox to verify your email so you can start receiving the latest in tech news and resources.


{{ parent.title || parent.header.title}}

{{ parent.tldr }}

{{ parent.urlSource.name }}