fix: add exptime to ewma shared dict items#12557
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Signed-off-by: Nic <[email protected]>
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Signed-off-by: Nic <[email protected]>
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Description
Because the current ewma load balancer uses two shared memory and has no recycling mechanism, when the user's upstream IP address changes frequently, the shared memory will be quickly consumed, resulting in the following error:
This PR sets expiration times for the two shared memory items used by ewma to record upstream latency data, so that when executing the
setandgetfunctions of sharedict, openresty will attempt to reclaim 1~2 expired entries.https://github.com/openresty/lua-nginx-module/blob/c47084b5d719ce507d2419d8660f39544a9d1fea/src/ngx_http_lua_shdict.c#L1595-L1599
https://github.com/openresty/lua-nginx-module/blob/c47084b5d719ce507d2419d8660f39544a9d1fea/src/ngx_http_lua_shdict.c#L1368
https://github.com/openresty/lua-nginx-module/blob/c47084b5d719ce507d2419d8660f39544a9d1fea/src/ngx_http_lua_shdict.c#L250-L254
This ensures that the shared memory space is released.
The choice of TTL
According to the current ewma algorithm parameters:
apisix/apisix/balancer/ewma.lua
Lines 51 to 58 in 3260931
apisix/apisix/balancer/ewma.lua
Line 20 in 49a48eb
set ttl to 60s is more appropriate because when the current time exceeds 60s from the
last_touched_at, the weight of that historical score is already close to 0. Therefore, whether or not this historical score exists does not matter.This error can only be triggered when there are frequent and continuous changes in the upstream nodes. so it is not able to provide an effective integration test.
Which issue(s) this PR fixes:
Fixes #
Checklist