[iotdb] branch master updated: Remove unnecessary lock in runningToFinshed of DriverScheduler

[ja...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

jackietien pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/iotdb.git


The following commit(s) were added to refs/heads/master by this push:
     new 96ab3086434 Remove unnecessary lock in runningToFinshed of DriverScheduler
96ab3086434 is described below

commit 96ab30864342d1d0b98c5eaad9570d2a204d7784
Author: Liao Lanyu <14...@qq.com>
AuthorDate: Wed May 31 19:51:54 2023 +0800

    Remove unnecessary lock in runningToFinshed of DriverScheduler
---
 .../iotdb/db/mpp/execution/schedule/DriverScheduler.java     | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/server/src/main/java/org/apache/iotdb/db/mpp/execution/schedule/DriverScheduler.java b/server/src/main/java/org/apache/iotdb/db/mpp/execution/schedule/DriverScheduler.java
index b043584c79a..d116a6fdcb6 100644
--- a/server/src/main/java/org/apache/iotdb/db/mpp/execution/schedule/DriverScheduler.java
+++ b/server/src/main/java/org/apache/iotdb/db/mpp/execution/schedule/DriverScheduler.java
@@ -543,13 +543,11 @@ public class DriverScheduler implements IDriverScheduler, IService {
       } finally {
         task.unlock();
       }
-      // wrap this clearDriverTask to avoid that status is changed to Aborted during clearDriverTask
-      task.lock();
-      try {
-        clearDriverTask(task);
-      } finally {
-        task.unlock();
-      }
+      // Wrapping clearDriverTask with task.lock() may lead to deadlock. For example:
+      // Thread A locks a task and then try to remove it from a SynchronizedSet(instance related
+      // tasks) which will try to get the lock of SynchronizedSet.
+      // Thread B locks the SynchronizedSet first and then tries to lock the task.
+      clearDriverTask(task);
     }
 
     @Override