You could use the python atexit module. On Wed, Jul 7, 2010 at 3:21 AM, Aaron Brenzel <[email protected]>wrote:
> Hi Anders, > > I put in a fix that thankfully didn't involve hacking the JPype source. > Basically, we moved the invocation of the GraphDatabaseService out of the > model and into the app globals. This ensures it's declared once for the > whole process and all threads use it, rather than each thread potentially > instantiating a new service and wreaking havoc with JPype. Hopefully > that's > a helpful hint to anyone using Pylons or a similar threaded Python web > environment with neo4j. > > There is still one outstanding issue, which is that taking down the server > still results in neo4j thinking it didn't shut down cleanly. Usually not a > huge deal, but if a lot nodes and edges were added during the server > session > it can result in a long recovery period (2-3 minutes) when the server boots > back up. I would guess this is because we're not getting a call into the > shutdown() method before the server process dies. Unfortunately > reimplementing the __del__ method to call it doesn't work because Python > doesn't guarantee __del__ will be called on a system exit. When we find a > good solution we'll be sure to post it. > > Best, > Aaron > > >Date: Tue, 06 Jul 2010 11:08:29 +0200 > >From: Anders Nawroth <[email protected]> > >Subject: Re: [Neo4j] CPython, Pylons, and threading > >To: Neo4j user discussions <[email protected]> > >Message-ID: <[email protected]> > >Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > > >Hi Aaron! > > > >It's probably a bug in JPype. At the moment nobody from the Neo4j team > >can look deeper into this, but maybe it's possible to check with the > >JPype project. Thread issues was recently discussed there: > > > http://sourceforge.net/mailarchive/message.php?msg_name=92CDD168D1E81F4F9D3839DC45903FC677EAB2E2%40dlee03.ent.ti.com > < > http://sourceforge.net/mailarchive/message.php?msg_name=92CDD168D1E81F4F9D3839DC45903FC677EAB2E2%40dlee03.ent.ti.com > > > > > > > >/anders > > > > > >On 07/04/2010 05:51 PM, Aaron Brenzel wrote: > > Hi everyone! > > > > Just wanted to say I really like neo4j so far and what it's capable of. > > It's helping to solve a lot of data modeling problems that were > impossible > > to handle in a RDBMS system. I'm using it with the Python bindings which > > are mostly intuitive so far, but I've been having an odd issue crop up. > > Despite the fact that it's a segmentation fault (I'll print the logs > below), > > it's not a show stopper because it only occurs on shutting down the > Pylons > > server (Paste Script 1.7.1) and does not crash the system. Here are the > > relevant pieces of the log: > > > > # > > # A fatal error has been detected by the Java Runtime Environment: > > # > > # SIGSEGV (0xb) at pc=0x08dae990, pid=16123, tid=3085936320 > > # > > # JRE version: 6.0_20-b02 > > # Java VM: Java HotSpot(TM) Client VM (16.3-b01 mixed mode linux-x86 ) > > # Problematic frame: > > # C [_jpype.so+0x3b990] _ZN9JPJavaEnv11NewLocalRefEP8_ > jobject+0x20 > > # > > # If you would like to submit a bug report, please visit: > > # http://java.sun.com/webapps/bugreport/crash.jsp > > # > > > > Stack: [0xbff41000,0xbff91000], sp=0xbff8f980, free space=13abff8f310k > > Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native > > code) > > C [_jpype.so+0x3b990] _ZN9JPJavaEnv11NewLocalRefEP8_jobject+0x20 > > C [_jpype.so+0x522a1] > > _ZN16JPMethodOverload14invokeInstanceERSt6vectorIP7HostRefSaIS2_EE+0x1c1 > > C [_jpype.so+0x61c1c] > > _ZN8JPMethod6invokeERSt6vectorIP7HostRefSaIS2_EE+0x5c > > C [_jpype.so+0x6bb73] > _ZN15PyJPBoundMethod8__call__EP7_objectS1_S1_+0x313 > > C [libpython2.6.so.1.0+0x2704c] PyObject_Call+0x5c > > C [libpython2.6.so.1.0+0xc1118] PyEval_EvalFrameEx+0x10d8 > > C [libpython2.6.so.1.0+0xc7ada] PyEval_EvalCodeEx+0x8ba > > C [libpython2.6.so.1.0+0xc5b24] PyEval_EvalFrameEx+0x5ae4 > > C [libpython2.6.so.1.0+0xc7ada] PyEval_EvalCodeEx+0x8ba > > C [libpython2.6.so.1.0+0x54659] > > C [libpython2.6.so.1.0+0x2704c] PyObject_Call+0x5c > > C [libpython2.6.so.1.0+0xc0da8] PyEval_EvalFrameEx+0xd68 > > C [libpython2.6.so.1.0+0xc7ada] PyEval_EvalCodeEx+0x8ba > > C [libpython2.6.so.1.0+0x5456a] > > C [libpython2.6.so.1.0+0x2704c] PyObject_Call+0x5c > > C [libpython2.6.so.1.0+0xbf304] PyEval_CallObjectWithKeywords+0x54 > > C [libpython2.6.so.1.0+0xea113] Py_Finalize+0xd3 > > C [libpython2.6.so.1.0+0xf7a64] Py_Main+0x4d4 > > C [python2.6+0x592] main+0x32 > > C [libc.so.6+0x15e9c] __libc_start_main+0xdc > > > > I am almost positive this is a thread issue. By default, the Pylons HTTP > > server starts up with a thread pool of 10 workers. These are POSIX > threads, > > which JPype should handle OK. However, my best guess is in the shutdown > > process Pylons is killing the threads before the JVM is finished > executing > > whatever code is going on in them, maybe some shutdown routines or > > something. Also, Pylons comes with a web-based debugger, which is > > essentially a web-based interface to the standard Python debugger. > > Attempting to use it for any code using the neo4j bindings causes an > > immediate segfault, probably because the debugger traces up and down the > > stack and is running into similar thread issues. > > > > Is there a way to ensure the threads detach from the JVM before dying or > > something similar to avoid this problem? Right now it is more annoying > than > > anything because it fills up the project's main directory with logs (we > are > > in active development and do a lot of server startup/shutdown) and makes > > debugging harder. It probably would not affect production stability when > we > > reach that stage because it is only happening while debugging or shutting > > down the server, but it is never good to release a project with a known > > segfault issue. > > > > Best, > > Aaron > > _______________________________________________ > > Neo4j mailing list > > [email protected] > > https://lists.neo4j.org/mailman/listinfo/user > _______________________________________________ > Neo4j mailing list > [email protected] > https://lists.neo4j.org/mailman/listinfo/user > -- Tobias Ivarsson <[email protected]> Hacker, Neo Technology www.neotechnology.com Cellphone: +46 706 534857 _______________________________________________ Neo4j mailing list [email protected] https://lists.neo4j.org/mailman/listinfo/user
