Commit timeouts on streams and slow queue/bus


We are seeing a lot of commit timeouts on streams which only get events that are emitted from projections

[PID:04936:043 2017.10.23 09:27:43.504 INFO CoreProjectionCheckp] Failed to write events to stream BackofficeRekeningSearch-Rekening-43731ea2-8f92-4376-9d74-7caa42735f0d. Error: CommitTimeout

What does that mean? Does this mean the event is not written to the stream? We have upgraded the storage to fast enterprise SSD’s and put the timeout to 20 000, just to be on the safe side.

Could this be related to traces like this:

[PID:04936:041 2017.10.23 09:27:54.785 TRACE QueuedHandlerMRES ] SLOW QUEUE MSG [Projection Core #0]: UnwrapEnvelopeMessage - 93ms. Q: 305/567.
[PID:04936:041 2017.10.23 09:27:54.941 TRACE InMemoryBus ] SLOW BUS MSG [bus]: UnwrapEnvelopeMessage - 109ms. Handler: UnwrapEnvelopeHandler.

What do these slow bus and slow queue mean?

Any thoughts on this?

Many thanks