[Truffle] Add tools for measuring startup time and memory consumption. #3296
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| max_iterations = 100 | ||
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| lower = 0 | ||
| upper = 4 * 1024 |
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It was just an initial size that was bound to be big enough. But now I think about it I can also search for the upper bound and not have one hard coded. I'll do that.
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Looks good. |
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@smarr please review if you have the time (especially https://github.com/jruby/jruby/pull/3296/files#diff-1c0dfa12324db9c68111f81e23be1ee6R1) |
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| private static void printTruffleMemoryMetric() { | ||
| if (Options.TRUFFLE_METRICS_MEMORY_USED_ON_EXIT.load()) { | ||
| System.gc(); |
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This seems to be problematic for multiple reasons.
Haven't yet read further in the changes, but, you are in the main method, and do a GC. So, I would expect, if there is no static state/memory leaks, after this GC, the used memory should be 0.
So, you might want to get the heap usage before the GC.
Also, System.gc() is really just a hint on HotSpot, you have to call it 3-4 times in succession to motivate HotSpot to actually do a collect (but, this then usually works).
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Ok, I now saw that you parse verbose:gc, nice. Ok, but you probably still want to call System.gc() multiple times to make sure it triggers. Then, I would assume that the verbose:gc output gives you a sum of all the objects that made it into GCed memory.
Looks good to me!
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JRuby has a great deal of static state (even though it is actually re-entrant) so I still need to check heap usage right at the end. Now I think about it I'm not sure what the point is of the GC at the end, given that I need to check heap usage after it anyway.
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side note: there may be a reliable way how to force gc in JVMTI, http://docs.oracle.com/javase/7/docs/platform/jvmti/jvmti.html#ForceGarbageCollection. I did not use it though.
[Truffle] Add tools for measuring startup time and memory consumption.
@pitr-ch @eregon @nirvdrum please review