What is the GPars default pool size?

Question

I thought this would have been an easy thing to find but I've failed.

If I use GPars in my Groovy application and I don't specify a pool size how many threads will be created? Is there a default pool size without setting one?

// How many threads will be created? What is the default pool size?
GParsExecutorsPool.withPool {
    // do stuff...
}

score 18 · Accepted Answer · answered Jan 12 '12 at 17:13

18

It is (by default) set to

private static int defaultPoolSize() {
  return Runtime.getRuntime().availableProcessors() + 1;
}

You can alter this (I believe) by setting a System property called gpars.poolsize to a valid Integer

answered Jan 12 '12 at 17:13

tim_yates

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Why is it "availableProcessors" plus one? I'd expect it to be minus one, to leave one available for other systems? (unless of course you only have one to begin with!) – Nick Grealy May 11 '16 at 05:57

score 8 · Answer 2 · answered Jan 12 '12 at 17:13

8

As many as you have CPU units plus one, as shown by the PoolUtils class source, or from a system property

retrieveDefaultPoolSize() is called once as a final static variable by the GParsPool class when it's initialized

answered Jan 12 '12 at 17:13

Grooveek

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Thanks, upvoted you for the source link. But had to give tim_yates the answer for being first :-) – C0deAttack Jan 12 '12 at 17:24

What is the GPars default pool size?

2 Answers2