Polling worker Tentacles are slower when running many concurrent deployments (or concurrent steps).

[LukeButters]

Severity

No response

Version

2023.3.8103 (with feature toggle) or since at least 2023.4.1479

Latest Version

None

What happened?

The problem

When running concurrent deployments which all use a single polling worker, deployments take longer.

Context:

1. Polling tentacles are limited to a single TCP connection to Octopus Server and can do at most one RPC at a time.
2. ScriptServiceV2 introduced a concept of waiting for the script to finish. see also PR
3. Octopus is using that durationToWaitForScriptToFinish with a value of 5s.
4. Tentacle workers usually run many scripts concurrently for many deployments concurrently.

Cause

The delay of 5s set on durationToWaitForScriptToFinish results in a bottle neck on starting scripts where multiple deployments may send a script to be executed by the worker, but must wait upto 5s for each other script the polling worker is starting.

Suggested Fix

Set durationToWaitForScriptToFinish to null when starting scripts on polling workers.

Reproduction

Create many deployments to a single polling worker, which have a mix of many steps bit each step takes longer than 5 secomds.

Error and Stacktrace

Start octopus with env var: OCTOPUS__Feature__LogTentacleRpcTimedOperationsWhenLongerThan_ms=0

Run the deployments as above.

Look for logs like:

Halibut RPC to tentacle calling IScriptServiceV2.StartScript succeeded after 11321ms.

That took 11.3s, which suggest it had to wait for two other scripts to start (2 x 5s) and then itself took 1.3s to run the script resulting in 10x worse performance.

More Information

No response

Workaround

Configure the polling tentacle to poll octopus server over many TCP connections by specifying other urls/ports to poll. For hosted users that can additionally poll the standard 443 port

by configuring their tentacle with:

/path/to/tentacle/Tentacle poll-server --server https://<yoururl>.octopus.app --apikey=API-APIKEY01 --server-comms-address "https://polling.<yoururl>.octopus.app" --server-comms-port=443