[pgrouting-dev] SSL SYSCALL error: EOF detected

[Stephen Woodbridge]

On 2/20/2015 5:58 AM, Luís de Sousa wrote:
> Dear all,
>
> I am presently implementing the Optimal Meeting Point (OMP) [0]
> algorithm with PyWPS. I have a draft brute force algorithm that in
> smaller networks computes the OMP correctly by testing all nodes of
> the network with pgr_dijkstra (I am not yet using heuristics since
> costs are not only distance dependent).
>
> I am now testing this algorithm in a larger network, of some 50 000
> nodes. I previously reported that for about 7%-8% of the nodes
> pgr_dijkstra fails, returning an empty tuple [1]. After patching these
> exceptions, I am stumping into another issue: somewhere between an
> half and two thirds of the network have been processed, Postgres
> crashes and I get the error: "SSL SYSCALL error: EOF detected" [2, 3].
> This crash seems to happen randomly, with pgr_dijkstra invoked on
> different nodes.

Hi Luís,

The error: "SSL SYSCALL error: EOF detected" is because the postgresql 
backend has crashed and you connection in python has terminated.

> This issue should also be easy to circumvent, but it seems to be
> symptom of something a bit more serious with pgrouting.

There are a number of things that can crash the database, like running 
out of memory, or running into a bug in the code.

google: gdb postgres stack trace

There are a couple of ways to get a stack trace of a crash.
1. is to enable core files
2. is to run the database under gdb

HTH,
   -Steve

> Regards,
>
> Luís
>
> [0] https://github.com/pgRouting/pgrouting/issues/289
>
> [1] http://pgrouting-users.974093.n3.nabble.com/pgrouting-users-Empty-tuple-from-pgr-dijkstra-tp4025706.html
>
> [2] http://stackoverflow.com/questions/20201711/pg-internalerror-ssl-syscall-error-eof-detected
>
> [3] http://stackoverflow.com/questions/20217571/psycopg2-interfaceerror-connection-already-closed-pgr-astar
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