Set SO_REUSEADDR again for wasmtime serve on unix#8738
Merged
alexcrichton merged 1 commit intoJun 3, 2024
Conversation
elliottt
approved these changes
Jun 3, 2024
alexcrichton
changed the title
SO_REUSEADDR again for wasmtime serveSO_REUSEADDR again for wasmtime serve on unix
alexcrichton
force-pushed
the
serve-port-options
branch
from
ccd2878 to
82a482c
Compare
This reverts part of bytecodealliance#7863 which was a misunderstanding on my part about `SO_REUSEADDR`. I think I mixed it up with `SO_REUSEPORT`. Without `SO_REUSEADDR` it's possible to have this happen on Unix: * Start a `wasmtime serve` session * Connect to the session with `nc` * Kill the server * Restarting the server no longer works Due to the active TCP connection at the time the server was killed the socket/address is in the `TIME_WAIT` state which apparently prevents rebinding the port until the OS has a chance to clean up everything. Setting `SO_REUSEADDR` enables rebinding the address quickly. Now in bytecodealliance#7863 that was trying to fix bytecodealliance#7852 which said that it was possible to have multiple `wasmtime serve` instances binding the same port. That can lead to confusion and is generally something we don't want. That being said bytecodealliance#7863 only fixed the issue for Windows but ended up making Unix worse. This PR restores more reasonable behavior for both Unix and Windows by conditionally setting the `SO_REUSEADDR` based on the platform. This PR additionally adds two new tests, both for rebinding an in-use port quickly and additionally ensuring the same port can't be listened to twice.
alexcrichton
force-pushed
the
serve-port-options
branch
from
82a482c to
d75df75
Compare
Member
Author
|
Ok turns out the issue was that we want |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
This effectively reverts #7863 which was a misunderstanding on my part about
SO_REUSEADDR. I think I mixed it up withSO_REUSEPORT. WithoutSO_REUSEADDRit's possible to have this happen:wasmtime servesessionncDue to the active TCP connection at the time the server was killed the socket/address is in the
TIME_WAITstate which apparently prevents rebinding the port until the OS has a chance to clean up everything. SettingSO_REUSEADDRenables rebinding the address quickly.Now in #7863 that was trying to fix #7852 which said that it was possible to have multiple
wasmtime serveinstances binding the same port. That can lead to confusion and is generally something we don't want. That being said #7863 didn't actually change anything on either macOS or Unix, although it did fix the issue on Windows. Turns out the fix for both these issues was to only turn offSO_REUSEADDRon Windows, but leave it on for Unix.This PR additionally adds two new tests, both for rebinding an in-use port quickly and additionally ensuring the same port can't be listened to twice.