Hi Dan, >From the segfault thread dump it looks like you are running at least 2 Python threads, is that correct? (Thread 0, and Thread 21)
>From the numbering of the threads I'm guessing Thread 0 is the thread that started the JVM (and Neo4j), and Thread 21 is the one that is shutting down Neo4j. Has Thread 21 opened any transactions with Neo4j before attempting to shut down Neo4j? When embedding a JVM through JNI (which is what JPype does) all operating system threads that are not started by the JVM needs to register with the JVM in order to be able to invoke any JVM methods. JPype does not do this automatically, instead it provides functions for the developer (me or you) to do this. I've added a check for new threads, and registrations thereof, in the function that opens a new transaction. This means that after opening a transaction (possibly closing it right away) a new thread should be able to utilize the Neo4j objects. If trying to interact with Neo4j without ever opening a transaction before doing so, any new thread could cause severe problems (of an undocumented kind. This usually means segfault). This is a bit of a wart, and I can't say with a 100% confidence that this is what has happened to you, but it's a theory, and now that it's presented to you, my hope is that you can be confident whether or not this applies to your code. Let me know if this was any help. Cheers, Tobias On Wed, Aug 18, 2010 at 10:55 PM, Dan Gould <d...@dangould.com> wrote: > > Hi, > > I'm experimenting with Neo4j.py. I want to completely clear my DB > between tests in my test framework, which I do with shutdown(), remove > the db dir, and restart (I've had problems removing all nodes; I'll > discuss in a separate thread on the list once I put together a simple test). > > When I call shutdown() on the Graph Database, I get a Segmentation Fault. > > I want to be able to shut down safely, so I was wondering if there is a fix. > > I'm running with: > - Neo4j.py (tried a few versions, including last night's svn HEAD; I > also tried changing pom.xml to use Neo4j 1.1) > - CPython: Python 2.6.5 (r265:79063, May 17 2010, 14:26:12) [GCC 4.2.1 > (Apple Inc. build 5646)] on darwin > - I have both JPype-0.5.4.1 and JCC-2.6 installed in my virtualenv (I > also tried with only JPype installed) > - OS X 10.6.3 > - Java Version "1.6.0_20"; Java(TM) SE Runtime Environment (build > 1.6.0_20-b02-279-10M3065); Java HotSpot(TM) 64-Bit Server VM (build > 16.3-b01-279, mixed mode) > > (I can also get a segfault if writing outside a transaction.) > ---8<--- <cut out long stack trace/> ---8<--- -- Tobias Ivarsson <tobias.ivars...@neotechnology.com> Hacker, Neo Technology www.neotechnology.com Cellphone: +46 706 534857 _______________________________________________ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
