[tmail.linagora.com] Redis outage makes JMAP unusable

[quantranhong1999]

We enabled eventBus.redis.failure.ignore=true, but when Redis is down, TMail seems still to be totally timeout.

Even a JMAP well-known request (that requires no Redis usage) is timeout too. My feeling is that Redis timeout somehow blocked our schedulers afterward sometimes.

Note that I still can do webadmin /healthcheck normally.

TODO: investigate the issue.
Suggestion: Let Redis be down for a good enough time, and fire many JMAP requests to TMail in the meantime to try to reproduce the total timeout issue.

Related materials that we may revise:

• JMAP - fault tolerance when Redis down james-project#5175
• Chaos testing: break down Redis #1013

cc @Arsnael @vttranlina

[chibenwa]

Casual suspects:

• blocking code on .parrallel or drivers rendering those unusable
• Suggestion: do a thread dump

[chibenwa]

(and 100% agree with the issue)