Fix deadlock during manual client reset #7696
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clementetb
changed the title
nhachicha
approved these changes
Jul 6, 2022
| @@ -307,7 +323,7 @@ synchronized void reset() { | |||
| * @param session Session to trigger Client Reset for. | |||
| */ | |||
| void simulateClientReset(SyncSession session) { | |||
| simulateClientReset(session, ErrorCode.DIVERGING_HISTORIES); | |||
| new Thread(() -> simulateClientReset(session, ErrorCode.DIVERGING_HISTORIES)).start(); | |||
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Maybe add a comment on why we run it on a separate thread (to simulate the error coming from the sync writer thread)
clementetb
commented
Jul 7, 2022
realm/realm-library/src/objectServer/java/io/realm/mongodb/sync/Sync.java
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Closes #7691
A deadlock will occur if we try to close the last Realm instance while inside a manual client reset block.
When we receive a sync error we acquire a lock on the
Syncinstance, while locked we are required to close all open Realm instances. This last instance would try to close the sync session, but it needs to acquire the lock that was previously acquired by the sync error logic.It was not captured in our tests because the simulated sync error method did not simulate that the error came from a different thread than the one being executed.
This PR addresses this issue by not acquiring the lock on client reset errors.