Fix race condition in json.Register #7
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MichaelSnowden
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Nov 16, 2023
<!-- Describe what has changed in this PR --> **What changed?** This PR updates our version of tchannel to one that contains this change: temporalio/tchannel-go#7. <!-- Tell your future self why have you made these changes --> **Why?** This should fix a rare race condition that happens where a tchannel is used while there are still handlers being added to it. <!-- How have you verified this change? Tested locally? Added a unit test? Checked in staging env? --> **How did you test it?** I didn't reproduce it actually, but it's a very small change, and the race condition is pretty clear to see. <!-- Assuming the worst case, what can be broken when deploying this change to production? --> **Potential risks** The only other changes pulled in from this upgrade were changes to the go.mod in tchannel-go, which look pretty innocuous: ``` - golang.org/x/net v0.0.0-20211015210444-4f30a5c0130f - golang.org/x/sys v0.0.0-20211019181941-9d821ace8654 + golang.org/x/net v0.7.0 + golang.org/x/sys v0.5.0 ``` <!-- Is this PR a hotfix candidate or require that a notification be sent to the broader community? (Yes/No) --> **Is hotfix candidate?** No, it can wait. This only comes up super rarely.
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What was changed
I changed the
json.Registerfunction to only invokeregistrar.Registerafter all handlers have been added to the map.Why?
It's possible for one of the handlers to be invoked after it has been registered with the registrar. Also, there's nothing stopping that from happening before we've finished writing to the
handlersmap, and thehandlerfunction reads from that same map, so this could lead to a data race.Checklist
Closes [Bug] Race: Concurrent map read/write, probably in server temporal#5123
How was this tested:
You can see a justification for this here: temporalio/temporal#5123 (comment).
It's hard to reproduce this in temporal itself because it's a very rare bug, so I'm not going to try. The change itself is small, so it should be easy to see if it goes away.
No.