Tips and Tricks

Setting Custom Pickle and Marshal Protocols

By default, Sheepdog uses Pickle protocol pickle.DEFAULT_PROTOCOL and marshal version marshal.version. These correlate to the default protocols for your current Python interpreter.

However, if your worker nodes are running an older Python than the computer running Sheepdog, you may need to decrease these protocols. For example, Python 3 uses Pickle protocol 3 by default, which is not compatible with any Python 2.

To change this, overwrite sheepdog.serialisation.pickle_protocol and sheepdog.serialisation.marshal_version:

>>> import sheepdog
>>> sheepdog.serialisation.pickle_protocol = 2
>>> sheepdog.map_sync(...)

Restarting The Server

Should the HTTP server that listens for requests and results from job workers die, any still-queued jobs will not be able to start, and any currently running jobs will not be able to submit results. Jobs do send their results to standard output, but it’s obviously better to get a server up again. You don’t have to resubmit the request, instead just start a new Server and keep it around until the job is complete. Here’s an example:

import sys
import time
import sheepdog
server = sheepdog.Server()
storage = sheepdog.Storage()
while True:
    n_results = storage.count_results(int(sys.argv[1]))
    print(n_results, "results\r", flush=True)

This code gets one request ID from the command line, starts a server (here using the default location of ‘./sheepdog.sqlite’ but you can change this in the Storage constructor) and waits for results to come in.

Finding Request IDs, Ports and Passwords

For getting results out of previously completed jobs you’ll need the request ID, but this isn’t obviously found if you’re just using the synchronous function. You can find these values by looking in the Sheepdog job files on the GridEngine server, instead. These files are by default placed in ~/.sheepdog and named like The final line contains a call to Client with the URL, password and request ID:

Client("", "hunter2", 12, job_index).go()

In this example the request ID is 12.