[GitHub] [apisix] nic-6443 opened a new pull request #6259: fix(config_etcd): skip resync_delay while etcd watch timeout

[GitBox <gi...@apache.org>]

nic-6443 opened a new pull request #6259:
URL: https://github.com/apache/apisix/pull/6259


   ### What this PR does / why we need it:
   <!--- Why is this change required? What problem does it solve? -->
   <!--- If it fixes an open issue, please link to the issue here. -->
   Discussion in mailing list: https://lists.apache.org/thread/pfkf88h7v515t29xh6csxhhfbhcbt77j
   
   > I have a problem with APISIX and I hope I can discuss it with you.
   > APISIX has a configuration item: `etcd.resync_delay`, the effect is to
   pause for a while before launching the next watch request when the method
   call of watch etcd returns an error.
   I understand that this logic is to protect the etcd server from being
   overloaded by uninterrupted retries by the client after an unintended
   exception.
   > I think this protection mechanism is reasonable, but one of the cases of
   error is timeout error, which means that no event is generated for the
   specified key within the time period of this watch (default 30s timeout),
   this kind of error is expected, because usually the configuration of the
   gateway does not change frequently, and at this time we do not have special
   handling for timeout error, so it will also cause the next watch call to be
   launched with a wait of `etcd.resync_delay` seconds. This is very
   dangerous.
   > For example: in the default configuration, when the user's upstream
   configuration does not change within 30s, apisix will suspend the
   synchronization configuration for about 6-7 seconds (5s+jitter), and apisix
   will not be able to respond to all changes to the upstream during this
   period.
   > So I think we should let the timeout error go and not take the resync delay
   logic. This is in line with the millisecond configuration synchronization
   requirements claimed in the apisix documentation.
   The impact of doing so: removing the resync delay after timeout error will
   cause apisix to have more concurrent etcd connections over time, for
   example, in the default configuration (`etcd.timeout=30,
   etcd.resync_delay=5`), the delay resync after timeout processing can reduce
   the number of concurrent connections by ~ 1/6(6/(6+30)). I think this
   impact is negligible compared to the configuration not taking effect in
   time.
   
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   * [x] Did you explain what problem does this PR solve? Or what new features have been added?
   * [x] Have you added corresponding test cases?
   * [ ] Have you modified the corresponding document?
   * [x] Is this PR backward compatible? **If it is not backward compatible, please discuss on the [mailing list](https://github.com/apache/apisix/tree/master#community) first**
   


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[GitHub] [apisix] spacewander merged pull request #6259: fix(config_etcd): skip resync_delay while etcd watch timeout

[GitBox <gi...@apache.org>]

spacewander merged pull request #6259:
URL: https://github.com/apache/apisix/pull/6259


   


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