This week I've run into a problem with the MSSEARCH wait type, and I haven't been able to fully diagnose the problem.
The server had been running with no problem for several weeks until the other day, when it suddenly started taking too long for replying to users' requests.
My team and I quickly found the problem to be located at the Full-text Search component, but we had no idea what was causing it. (FTS is a feature heavily used in our workload and we've had no issues with it up until now.)
We tried restarting the MSFTE service, but it wouldn't respond.
As the screenshot above shows, the server was just below 400 Waiting Tasks (normal workload of under 10) and rising.
I didn't have too much time to try and diagnose it before restarting our server because we it was running in production, so I was left only with SQL Server's logs and a couple of MSFTE memory dumps after the full server restart.
I was expecting to be able to have a better understanding of the problem with those, but I wasn't able to acquire much information out of those, so I would be really glad if anyone would offer a pointer or shed some light into this.
All we were able to deduce was that the Full-text Search service had stopped working, but I found no evidence of such a bug on the web, and although it seems to be running ok now, I'd like to really understand what happened and prevent it from happening again.