[Swift-devel] Delay when coasters are shutting down

[wilde at mcs.anl.gov]

Mihael,

There seems to be a brief (~ 2-5 second) delay at the end of a run when swift seems to be shutting down the coaster service. (See example below)

This delay degrades performance for the Swift R interface, where an R script will be running many separate Swift scripts, one for each call to parallel apply().

Can this delay be readily eliminated? If its not present for persistent coasters, then that's not a problem. I'll look into it when I get a chance, but a pointer to where in the code the delay occurs would be helpful.

Eventually we'll have an R script make multiple calls to the same Swift JVM for successive apply() calls. That in fact would be a better place to focus than eliminating this delay.

In the R interface, we use a pair of FIFOs to communicate pass calls from a Swift app() script to persistent R server processes, one per Swift worker slot. We could use the same approach (and/or sockets) to provide a client interface for running multiple Swift calls from the same JVM.

Thanks,

- Mike

swift output is in: swift.stdouterr.0745, pids in swift.workerpids.0745
Swift svn swift-r3591 cog-r2868 (cog modified locally)

RunID: 20100902-1058-k58r43yg
Progress:
Passive queue processor initialized. Callback URI is http://128.135.125.18:50003
/home/wilde/SwiftR/passive-coaster-swift: Coaster contact: http://128.135.125.18:50003
/home/wilde/SwiftR/passive-coaster-swift: started workers from these ssh processes: 30864
logilename: /home/wilde/swiftworkerlogs/worker-42.log
Progress:  Active:1
Final status:  Finished successfully:1
Cleaning up...
Shutting down service at https://128.135.125.18:50002
Got channel MetaChannel: 1855107489[1623980477: {}] -> null[1623980477: {}]
+ Done

<<< Delay occurs here: swift command doesn't exit for a few seconds after the "Cleaning up..." message >>>

Exitting, terminating worker processes 30864 and starter 30747:
bri$ 


-- 
Michael Wilde
Computation Institute, University of Chicago
Mathematics and Computer Science Division
Argonne National Laboratory