Multi commands run slowly

[kevsmith]

The overhead of using a separate container for each command invocation adds between 0.5 and 1 second of overhead to each command call.

This winds up becoming intolerably slow on large pipelines or short pipelines with lots of output.

[kevsmith]

Example execution:

INFO[2016-05-11T12:05:33-04:00] Docker container 3a8abb4b7c4e ran circle:list for 1.241198 secs.
DEBU[2016-05-11T12:05:33-04:00] Dynamic config not found. Checked: '/Users/imbriaco/.cog/bundle_configs/format/config.yaml' and '/Users/imbriaco/.cog/bundle_configs/format/config.yml'.
INFO[2016-05-11T12:05:33-04:00] Docker container 0fb233c6e814 ran format:table for 0.693150 secs.
INFO[2016-05-11T12:05:33-04:00] (P: c6b06b4ac0d348248c7799114e0b1b19 C: format:table) Accumulated input data in 0.005415896 seconds.
DEBU[2016-05-11T12:05:33-04:00] Dynamic config not found. Checked: '/Users/imbriaco/.cog/bundle_configs/format/config.yaml' and '/Users/imbriaco/.cog/bundle_configs/format/config.yml'.
INFO[2016-05-11T12:05:34-04:00] Docker container 86d78e848140 ran format:table for 0.805931 secs.
INFO[2016-05-11T12:05:34-04:00] (P: c6b06b4ac0d348248c7799114e0b1b19 C: format:table) Accumulated input data in 0.007490317 seconds.
DEBU[2016-05-11T12:05:34-04:00] Dynamic config not found. Checked: '/Users/imbriaco/.cog/bundle_configs/format/config.yaml' and '/Users/imbriaco/.cog/bundle_configs/format/config.yml'.
INFO[2016-05-11T12:05:35-04:00] Docker container de12d8e7294a ran format:table for 0.675244 secs.
INFO[2016-05-11T12:05:35-04:00] (P: c6b06b4ac0d348248c7799114e0b1b19 C: format:table) Accumulated input data in 0.005320507 seconds.

[kevsmith]

Made some progress on this issue but more remains to be done. Current potentially shippable code is on go-relay/invocation-endpoints. Code on this branch doesn't cache and reuse containers but it does shut them down asynchronously which saves 0.3 - 0.5 seconds per invocation.

Caching and reuse of containers is proving to be trickier than I expected due to issues around managing container IO. The current state of this work, which is definitely NOT ready to ship, is on go-relay/invocation-endpoints-caching.

[kevsmith]

PR submitted this morning to operable/go-relay: #17