5af632e9ca
Conductor RPC calls the scheduler to get hosts during server create, which in a multi-create request with a lot of servers and the default rpc_response_timeout, can trigger a MessagingTimeout. Due to the old retry_select_destinations decorator, conductor will retry the select_destinations RPC call up to max_attempts times, so thrice by default. This can clobber the scheduler and placement while the initial scheduler worker is still trying to process the beefy request and allocate resources in placement. This has been recreated in a devstack test patch [1] and shown to fail with 1000 instances in a single request with the default rpc_response_timeout of 60 seconds. Changing the rpc_response_timeout to 300 avoids the MessagingTimeout and retry loop. Since Rocky we have the long_rpc_timeout config option which defaults to 1800 seconds. The RPC client can thus be changed to heartbeat the scheduler service during the RPC call every $rpc_response_timeout seconds with a hard timeout of $long_rpc_timeout. That change is made here. As a result, the problematic retry_select_destinations decorator is also no longer necessary and removed here. That decorator was added in I2b891bf6d0a3d8f45fd98ca54a665ae78eab78b3 and was a hack for scheduler high availability where a MessagingTimeout was assumed to be a result of the scheduler service dying so retrying the request was reasonable to hit another scheduler worker, but is clearly not sufficient in the large multi-create case, and long_rpc_timeout is a better fit for that HA type scenario to heartbeat the scheduler service. [1] https://review.openstack.org/507918/ Change-Id: I87d89967bbc5fbf59cf44d9a63eb6e9d477ac1f3 Closes-Bug: #1795992
8 lines
300 B
YAML
8 lines
300 B
YAML
---
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fixes:
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The ``long_rpc_timeout`` configuration option is now used for the RPC
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call to the scheduler to select a host. This is in order to avoid a
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timeout when scheduling multiple servers in a single request and/or when
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the scheduler needs to process a large number of hosts.
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