maglev: fix maglev stability by sorting host_weights beforehand #28055
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Signed-off-by: Yuichiro Ueno <ueno@preferred.jp>
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Hi @y1r, welcome and thank you for your contribution. We will try to review your Pull Request as quickly as possible. In the meantime, please take a look at the contribution guidelines if you have not done so already. |
KBaichoo
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Jun 22, 2023
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/wait |
Signed-off-by: Yuichiro Ueno <ueno@preferred.jp>
Signed-off-by: Yuichiro Ueno <ueno@preferred.jp>
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/retest |
KBaichoo
previously approved these changes
Jun 23, 2023
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need merge main and resolve the conflict. Thanks. /wait |
Signed-off-by: Yuichiro Ueno <ueno@preferred.jp>
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…yproxy#28055) * maglev: fix maglev stability by sorting host_weights beforehand Signed-off-by: Yuichiro Ueno <ueno@preferred.jp> Signed-off-by: asheryer <asheryer@amazon.com>
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…yproxy#28055) * maglev: fix maglev stability by sorting host_weights beforehand Signed-off-by: Yuichiro Ueno <ueno@preferred.jp> Signed-off-by: Ryan Eskin <ryan.eskin89@protonmail.com>
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Commit Message:
This PR fixes MaglevLoadBalancer's stability problem reported in #20703. Maglev algorithm prepares hash table by visiting permutations (assignment preference list of each backend) one-by-one, then fill hash table by choosing key from the top of the list. The order of permutation visiting should be stable because this order sightly affects the hash table. In order to make stable the order, I sorted
host_weightsbykey_to_hashvalue then constructs the hash table.In order to check the problem is solved or not, I appended BasicStability test to
maglev_lb_test.cc. Without changes tomaglev_lb.cc, this test will fail.Additional Description:
Risk Level: Low
Testing: Unit Test
Docs Changes:
Release Notes: loadbalancer: maglev now returns stable key assignment by sorting the backend beforehand
Platform Specific Features:
Fixes #20703