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<div class="gmail_quote">On Thu, May 3, 2012 at 9:35 PM, Krystal Mok <span dir="ltr"><<a href="mailto:rednaxelafx@gmail.com" target="_blank">rednaxelafx@gmail.com</a>></span> wrote:<br>
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<div class="im">On Fri, May 4, 2012 at 8:48 AM, Xin Tong <span dir="ltr"><<a href="mailto:xerox.time.tech@gmail.com" target="_blank">xerox.time.tech@gmail.com</a>></span> wrote:<br>
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<div>On Thu, May 3, 2012 at 8:45 PM, Xin Tong <<a href="mailto:xerox.time.tech@gmail.com" target="_blank">xerox.time.tech@gmail.com</a>> wrote:<br>> On Thu, May 3, 2012 at 8:29 PM, Krystal Mok <<a href="mailto:rednaxelafx@gmail.com" target="_blank">rednaxelafx@gmail.com</a>> wrote:<br>
>> On 2012-5-4, at 8:16, Xin Tong <<a href="mailto:xerox.time.tech@gmail.com" target="_blank">xerox.time.tech@gmail.com</a>> wrote:<br>>><br>>>> i would like to know how to debug in hotspot, what are some of the<br>
>>> standard procedures ? Lets say, the hotspot fails to run a Java<br>>>> program. a few steps to triage the problem.<br>>>><br>>>> 1. disable JIT compilers. hotspot has 2 compilers c1 and c2. they are<br>
>>> both used if TieredCompilation is enabled. How do I disable both of<br>>>> them.<br>>><br>>> It's there in the globals.hpp file: -XX:-UseCompiler<br></div></blockquote>
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<div>I forgot to mention there's a shorter (and better supported) equivalent to this: -Xint</div>
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<div>>><br>>>> 2. if the Java program passes after the JIT is disabled. There is a<br>>>> good chance that the problem is cause by the JIT. I want to narrow<br>>>> down to a specific method, I can use PrintCompilation to find out all<br>
>>> the method compiled, but how can I disable one specific method from<br>>>> being compiled.<br>>><br>>> -XX:CompileCommand='exclude,your/class,yourMethod'<br>>> Or an equivalent .hotspot_compiler configuration file.<br>
>> Read this thread for example (in Chinese): <a href="http://hllvm.group.iteye.com/group/topic/28201" target="_blank">http://hllvm.group.iteye.com/group/topic/28201</a><br><br></div>By the way, one thing we can do here is to force c1 to compile a<br>
method. i.e. c2 is more likely to fail than c1 as it does more<br>optimizations. how do i force c1 to compile a method ?</blockquote>
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<div>What platform and version of JDK are you using?</div>
<div>If there's a Client VM for your platform, use that;</div>
<div>If you're using JDK7 or JDK8, try -XX:+TieredCompilation -XX:TieredStopAtLevel=1, which effectively disables C2 in tiered mode.</div>
<div>Otherwise, if you have to use the Server VM (for instance, on amd64 where Oracle doesn't provide a Client VM build), and you're using an old version of JDK6, I'm not sure if there's a way to force compilation with C1.</div>
<div>And, there's no way (yet) to force compilation with C1/C2 on a per-method granularity.</div></div></blockquote>
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<div>There is no way to force the compilation with C1/C2 on a per-method granularity. But methods are compiled with C1 and then C2 in a tiered compilation , right ?</div>
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<div>Xin </div>
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<blockquote style="BORDER-LEFT:#ccc 1px solid;MARGIN:0px 0px 0px 0.8ex;PADDING-LEFT:1ex" class="gmail_quote">and how do i<br>know which compiler is used to compile a method in the<br>PrintCompilation log or through any other options ?<br>
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<div>Please refer to this note: <a href="https://gist.github.com/1165804#file_notes.md" target="_blank">https://gist.github.com/1165804#file_notes.md</a></div>
<div>I was supposed to put this up in the HotSpotInternals wiki, but somehow I haven't done it yet...oops.</div>
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<div>- Kris</div>
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<div><br>>><br>>>> 3. if i am able to limit down to a specific method, i want to start<br>>>> disabling optimizations, is there an option to disable all<br>>>> optimizations in the c1 and c2 compilers, or i need to do it manually<br>
>>> ?<br>>>><br>>><br>>> I don't think there's an all-in-one flag to turn all optimizations off. At least not for now.<br>>> See c1_globals.hpp and c2_globals.hpp to get an idea of what optimizations you can turn off.<br>
>><br>>> - Kris<br>>><br>>>> Thanks<br>><br>> Thank you very much Kris. This is very helpful.<br></div></div></blockquote></div></div><br></blockquote></div><br>