CODEWITHSUNDEEP
performancegarbage-collectionjava-7java-5
harshavmb
harshavmb

Reputation: 3872

Java7 vs java5 garbage collection

We are planning to migrate our enterprise application currently running on Java5 stack to Java7 stack. We are having issues with implicit gc calls (mainly major gc) causing system to be unstable for a short time(ranging from 5 mins - 30 mins). After analyzing the gc stats, we found that Compact phase is taking quite long time to complete when compared to Mark and sweep phase. I understand compaction is quite complex and time taking but its impacting the app server which is customer facing and few connections being dropped off during this phase.

Now, my question is as we are migrating to Java7, is there a better garbage collection process compared to Java5?

App servers are provided with decent system resources.

  1. Each app server contains 32 cpu cores
  2. contains 64 gb ram
  3. App server is IBM webpshere server
  4. Operating System - 64 bit IBM AIX

As said earlier, gc is happening because of implicit system calls. No explicit system calls invoking gc.

Upvotes: 2

Views: 98

Answers (3)

Stephen C
Stephen C

Reputation: 718718

Now, my question is as we are migrating to Java7, is there a better garbage collection process compared to Java5?

Generally yes, though as @Pushkar, you should really be migrating to Java 8.

With respects to the specifics of your application(s), it sounds like you need to tune / retune the garbage collection on Java 5. If you are periodically experiencing 5 to 30 >>minutes<< of unstability due to GC, there is something rather wrong. The current behavior may be due your application or Websphere (e.g. memory leaks, excessive caching, etc), or it may be due to poor GC tuning.

In short, switching to Java 7 (or 8) might make things better "out of the box", but it is likely that you will need to put in more effort to address the underlying cause of your problems.

Finally, I'd advise the obvious things.

  • Implement the changes in small steps. Don't upgrade your app, websphere version, java version, etc all at the some time.

  • Do the upgrades of your servers one at a time. Have a roll-back plan in case you get unacceptable performance.

  • If possible test it all first ... including performance / load testing.

Upvotes: 1

Pushkar
Pushkar

Reputation: 571

Java 7 reached end of life around April 2015. Why not migrate to 1.8?

GC performance usually improves with java major releases (and in some cases with minor GCs).

You should take a look difference GC tuning flags, following link may help you http://www.oracle.com/technetwork/articles/java/vmoptions-jsp-140102.html

http://stas-blogspot.blogspot.com/2011/07/most-complete-list-of-xx-options-for.html

Upvotes: 1

Balaji Sukumaran
Balaji Sukumaran

Reputation: 185

By default, java 7 uses parallelGC on server class machines. If you are using JDK 7 update 4 or later version, switch to G1 garbage collector which might give you better performance. But as @the8472 suggested,it will be good to know what settings you used in java 5 and now in your current environment.

Upvotes: 1

Related Questions