Closed Bug 1094522 Opened 5 years ago Closed 5 years ago

Investigate why HTTP/2 test runs over 2 different connections

Categories

(Core :: Networking: HTTP, defect, minor)

defect
Not set
minor

Tracking

()

RESOLVED FIXED
mozilla38

People

(Reporter: u408661, Assigned: mcmanus)

References

Details

(Whiteboard: [spdy])

Attachments

(2 files)

I noticed this while debugging my tests for bug 1091263. As it turns out, we end up with two different HTTP/2 sessions when running test_http2.js. The first connection is used by the first test, and the second connection is used by all subsequent tests (unless there's a test that explicitly causes a new connection). This happens regardless of which test is first, and regardless of how many tests are in the suite. This was really annoying when I was running just a new subset of the tests that were supposed to share a connection, and they didn't. Once I re-enabled the rest of the tests (that were run before my new tests), everything was fine.

This isn't the end of the world, but we should see if we can figure out why this happens, and also if it ever happens in the real world.
I think I diagnosed this on the test_spdy side, which sees a similar thing.

A sepculative connect starts a connection, and the tcp handshake completes before the connection manager has a transaction for it yet. (in this case that's cause the connect is to localhost - so its wicked fast). So the connection manager drives the ssl handshake with a null transaciton.

but before the null transaction has completed the http request arrives in the connection manager and that starts a new connection up because there are no idle or active-spdy connections.

give it a few milliseconds and you've got 2 sessions.

There actually is code in makenewconnections() that looks for a sepculative half open connection.. and if it finds such a thing it claims it for itself rather than making a new connection. I think the issue can be fixed by extending that logic to active null transactions as well.
Blocks: 1102923
Assignee: nobody → mcmanus
Status: NEW → ASSIGNED
Attachment #8555851 - Flags: review?(hurley) → review+
Attachment #8556095 - Flags: review?(hurley) → review+
https://hg.mozilla.org/mozilla-central/rev/050e9b432799
https://hg.mozilla.org/mozilla-central/rev/c4cccb7acc1b
Status: ASSIGNED → RESOLVED
Closed: 5 years ago
Resolution: --- → FIXED
Target Milestone: --- → mozilla38
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