OWA: Too many connections, and 100% CPU when searching for persons

[benbucksch]

Reproduction

1. Setup a few mail accounts with a realistic amount of email and contacts
2. Open the Vertical view
3. Switch to Person view
4. Click on 1-2 persons

Actual result

• CPU fan spins up, with 100% CPU, for multiple minutes
• Error: "Error: Too many concurrent connections opened., Cannot open mailbox"

  Error: Too many concurrent connections opened., Cannot open mailbox. Server = ....EURP191.PROD.OUTLOOK.COM, mdbGuid = ..., maiboxGuid = ...
  at OWAAccount.callOWA (/logic/Mail/OWA/OWAAccount.ts:136:13)
  at async OWAEMail.markRead (/logic/Mail/OWA/OWAEMail.ts:91:5)

• The display updates every 30 to 60 seconds
• The Mustang window keeps grabbing focus away from other windows, e.g. the browser tab that I'm typing into here, interfering with the bug report filing.
• Mustang is essentially locked up since 5-10 minutes, and I cannot even close it.

Expected result

• No server calls
• A single SQL query matching the person selected
• Results display immediately
• Low CPU usage, and only for a split-second

[NeilRashbrook]

I don't make server calls if the UI doesn't ask for them. The OWA code is very similar to the IMAP code in that it unconditionally makes a server call every time the UI marks a message as read. I assume you're getting away with this in IMAP because the library requires you to lock the mailbox effectively serialising the requests?

I have no idea why your UI might be trying to grab focus. is it doing this in response to trying to display the error banner?

[benbucksch]

I assume the OWA calls that caused the server overload were not the markRead() calls, but that this just happens to be the last one, and the server had already locked us out at this point. The OWA call that caused the overload was most likely another call.

FWIW, my paid (!) @outlook.com account was locked due to "terms of use violations" (maybe because of this bug, impossible to tell), so I cannot test anymore. This is a serious bug that might cause the user harm beyond Mustang, so we have to get this fixed.

[benbucksch]

Did you try the reproduction? Make sure to use a fresh @outlook.com account that you don't need.

[NeilRashbrook]

I tried the reproduction with the Office 365 account but I didn't even hit my breakpoint on callOWA once, so your STR are insufficient.

[benbucksch]

There are 2 problems here:

• The UI is triggering too many requests at the same time. I know it's caused by the Persons search, because I observed it, but I don't know where and how exactly. That's a bug in the UI and to be debugged.
• Our OWA client is overloading the server. #153

(Typo corrected)

[NeilRashbrook]

Don't you mean our OWA client?

[benbucksch]

I did. Corrected.