Java Profilers - Which One Are You Using?

splitPersonality asks: "Our Java programmers are researching various profilers to use in-house. We would appreciate some feedback from other shops that are using Java profilers. Along with the specific product, would you please include reasons behind your choice? If you now have misgivings about the one you or your shop chose, please let me know about those, as well."

Comments

PerfAnal.jar

[edwinolson]

Believe it or not, I do most of my profiling by running by using:

alias java-prof='java -agentlib:hprof=cpu=samples,depth=8,interval=1,thr ead=y'

And then I view the results with PerfAnal.jar (google will find it for you), an extremely old (and even ugly) GUI that is also clean and mean. It's also free (beer? not sure.)

I've tried a number of other profilers (JFluid, YAJP, etc.), and they usually prove to be too much of a pain in the ass, or just give nonsense data.

Mind you, I'm usually interested in pure CPU performance-- tightening inner loops and things like that. I don't care too much about memory profiling or garbage collector behavior since I've long since eliminated most allocations in my performance-sensitive code.

Sadly, no profiler really satisfy me. Usually, line-by-line CPU usage just can't be computed given the optimization performed by HotSpot: you'll see trace-by-trace CPU usage, where a trace covers several lines of code. It makes it hard to know exactly where the CPU time is being spent. (You can run with -Xint, but the performance is so different without HotSpot that it's not helpful.)

JProfiler

[Wizard of OS]

Interesting to see this question come up just a week after I was in deperate need of a profiler. I downloaded JProfiler 4.2 and got a test-license (for 10 days or so). (oh, and I work on a Mac, and it has downloads for 3 platforms).

The problem I had was the following. We upgraded our system from the previous stable release of our opensource CMS to the new stable release. We knew a lot had changed in the internals, so we did a good functional testround and fixed quite a few issues. Quite confident in the new software (it appeared faster) we deployed on our live environment. Looked fine, until after a few hours it didn't stop Full-GC-ing, the symptoms of a memory leak. (and yes, I know how to tune my VM to optimum GC performance).

All I can say about JProfiler is that after only 3 or 4 days, I found all memory leaks, several performance issues (even things like 'for (int i=0; istr.length(); i++)'), and got a real good feel about the bottlenecks inside the application. My manager just bought me a $400 or so license, and it's money very well spent.

So next week we'll go live again, but now with a piece of software of which we exactly know how it behaves.

I suggest you download the evaluation version and just give it a try. I can't imagine putting a release live anymore, without having profiled it for at least a day.