Posgres: fix concurrency in channels db #1762
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This test unveils a concurrency issue in the upsert logic of the local channels db, with the following error being thrown when we update many channels concurrently: ``` Canceled on identification as a pivot, during conflict out checking ```
This is the recommended pattern according to postgres doc (https://www.postgresql.org/docs/current/plpgsql-control-structures.html#PLPGSQL-UPSERT-EXAMPLE): > It is recommended that applications use INSERT with ON CONFLICT DO UPDATE rather than actually using this pattern.
t-bast
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Apr 12, 2021
eclair-core/src/main/scala/fr/acinq/eclair/db/pg/PgChannelsDb.scala
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We probably do! Will do a pass on all other db calls. |
Done with bb93ee5. |
t-bast
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Apr 12, 2021
Codecov Report
@@ Coverage Diff @@
## master #1762 +/- ##
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+ Coverage 89.17% 89.24% +0.07%
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Files 143 143
Lines 10772 10768 -4
Branches 477 464 -13
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+ Hits 9606 9610 +4
+ Misses 1166 1158 -8
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The upsert pattern in
channelsDb.addOrUpdateChannelis apparently not compatible with concurrent transactions when they are inSERIALIZABLEmode.A simple test shows the issue and the following exception is thrown:
I tried reducing the isolation level, but 1) I'm not sure what the consequences are in terms of locking the db and 2) it didn't entirely fix the issue.
As per the postgres doc, the recommended construct for the upsert pattern is with the
ON CONFLICTclause:I'm not sure about the performance of this (we mostly do updates, so we will run into the
ON CONFLICTa lot), but let's first make it work.