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| author | Richard van der Hoff <richard@matrix.org> | 2020-08-29 00:05:25 +0100 |
|---|---|---|
| committer | Richard van der Hoff <richard@matrix.org> | 2020-08-29 00:06:00 +0100 |
| commit | 8027166dd546811316e7c8395deaf929110c2f3a (patch) | |
| tree | ee4fa7bb1d4b94adfffc8af5c68d59ac4145f057 /synapse/app/_base.py | |
| parent | Convert ReadWriteLock to async/await. (#8202) (diff) | |
| download | synapse-8027166dd546811316e7c8395deaf929110c2f3a.tar.xz | |
Add a comment about _LimitedHostnameResolver
Diffstat (limited to '')
| -rw-r--r-- | synapse/app/_base.py | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/synapse/app/_base.py b/synapse/app/_base.py index 2b2cd795e0..a43dc5b2c9 100644 --- a/synapse/app/_base.py +++ b/synapse/app/_base.py @@ -334,6 +334,13 @@ def install_dns_limiter(reactor, max_dns_requests_in_flight=100): This is to workaround https://twistedmatrix.com/trac/ticket/9620, where we can run out of file descriptors and infinite loop if we attempt to do too many DNS queries at once + + XXX: I'm confused by this. reactor.nameResolver does not use twisted.names unless + you explicitly install twisted.names as the resolver; rather it uses a GAIResolver + backed by the reactor's default threadpool (which is limited to 10 threads). So + (a) I don't understand why twisted ticket 9620 is relevant, and (b) I don't + understand why we would run out of FDs if we did too many lookups at once. + -- richvdh 2020/08/29 """ new_resolver = _LimitedHostnameResolver( reactor.nameResolver, max_dns_requests_in_flight |