Author: Richard Plangger <planri...@gmail.com> Branch: extradoc Changeset: r5658:8bb00903feae Date: 2016-08-01 10:19 +0200 http://bitbucket.org/pypy/extradoc/changeset/8bb00903feae/
Log: draft for jitlog blog post diff --git a/blog/draft/new-jit-log.rst b/blog/draft/new-jit-log.rst new file mode 100644 --- /dev/null +++ b/blog/draft/new-jit-log.rst @@ -0,0 +1,54 @@ +PyPy's Toolbox got a new Hammer 🔨 +======= + +Tools, tools, tools! It seems that PyPy cannot get enough of them! +In the last winter sprint (Leysin) covered the current tool for observing interals of the JIT compiler (JitViewer). VMProf at that time already proved that it is a good tool for CPU profiles. We are happy to release a new version of VMProf incooperating a rewritten version of JitViewer. + +The old logging format, is a hard to maintain plain text logging facility. Frequent changes often broke internal tools most notably the JITViewer. A second bad taste is that the logging output of a long running program takes a lot of space. + +Our new binary format encodes data densly, makes use of some compression (gzip) and tries to remove repetition where possible. On top of that protocol supports versioning and can be extended easily. And! *durms* you do not need to install JitViewer yourself anymore. The whole system moved to vmprof.com and you can use it any time free of charge. + +Sounds great. But what can you do with it? Here are two examples useful for a PyPy user: + +PyPy crashed? Did you discover a bug? +------------------- + +For some hard to find bugs it is often necessary to look at the compiled code. The old procedure often required to upload a plain text file which was hard to parse and to look through. + +The new way to share a crash report is to install vmprof and execute either of the two commands: + +``` +# this program does not crash, but has some weird behaviour +$ pypy -m jitlog --web <your program args> +... +PyPy Jitlog: http://vmprof.com/#/<hash> +# this program segfaults +$ pypy -m jitlog -o /tmp/log <your program args> +... +<Segfault> +$ pypy -m jitlog --upload /tmp/log +PyPy Jitlog: http://vmprof.com/#/<hash> +``` + +Providing the link in the bug report enables PyPy developers browse and identify potential issues. + +Speed issues +------------ + +VMProf is a great tool to find out hot spots that consume a lot of time in your program. As soon as you have idenified code that runs slow, you can switch to jitlog and maybe pin point certain aspects that do not behave as expected. You will find not only the overview, but are also able to browse the generated code. If you cannot make sense of that all you can just share the link with us and we can have a look at the compiled code. + +Future direction +---------------- + +We hope that the new release will help both PyPy developers and PyPy users resolve potential issues and easily point them out. + +Here are a few ideas what might come in the next few releases (). + +* Extend vmprof.com to be able to query vmprof/jitlog. Some times it is interesting to search for specific patterns the compiler produced. An example for vmprof: 'methods.callsites() > 5' and for the jitlog would be 'traces.contains('call_assembler').hasbridge('*my_func_name*')' + +* Combination of CPU profiles and the JITLOG (Sadly did not make it into the current release) + +* Extend the jitlog to capture the information of the optimization stage + +plan_rich and the PyPy team + _______________________________________________ pypy-commit mailing list pypy-commit@python.org https://mail.python.org/mailman/listinfo/pypy-commit
