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Change synchronized on FileSystemContext to avoid deadlock #16219

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Merged
alluxio-bot merged 2 commits into from
Oct 9, 2022
+11 −7
Merged

Change synchronized on FileSystemContext to avoid deadlock #16219

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f3b2c60
Resolve deadlocks in FileSystemContext by removing 'synchronized'
elega Sep 20, 2022
b01cbe4
update
elega Sep 23, 2022
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18 changes: 11 additions & 7 deletions core/client/fs/src/main/java/alluxio/client/file/FileSystemContext.java
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Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,7 @@
import java.util.Optional;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;
import javax.annotation.Nullable;
import javax.annotation.concurrent.GuardedBy;
import javax.annotation.concurrent.ThreadSafe;
Expand Down Expand Up @@ -159,11 +160,11 @@ public class FileSystemContext implements Closeable {
private boolean mUriValidationEnabled = true;

/** Cached map for workers. */
@GuardedBy("this")
private volatile List<BlockWorkerInfo> mWorkerInfoList = null;
@GuardedBy("mWorkerInfoList")
private final AtomicReference<List<BlockWorkerInfo>> mWorkerInfoList = new AtomicReference<>();

/** The policy to refresh workers list. */
@GuardedBy("this")
@GuardedBy("mWorkerInfoList")
private final RefreshPolicy mWorkerRefreshPolicy;

private final Map<Class, BlockLocationPolicy> mBlockLocationPolicyMap;
Expand Down Expand Up @@ -636,11 +637,14 @@ public synchronized WorkerNetAddress getNodeLocalWorker() throws IOException {
*
* @return the info of all block workers eligible for reads and writes
*/
public synchronized List<BlockWorkerInfo> getCachedWorkers() throws IOException {
if (mWorkerInfoList == null || mWorkerInfoList.isEmpty() || mWorkerRefreshPolicy.attempt()) {
mWorkerInfoList = getAllWorkers();
public List<BlockWorkerInfo> getCachedWorkers() throws IOException {
synchronized (mWorkerInfoList) {
if (mWorkerInfoList.get() == null || mWorkerInfoList.get().isEmpty()
|| mWorkerRefreshPolicy.attempt()) {
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@jiacheliu3 jiacheliu3 Sep 23, 2022

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do we need to worry about the thread safety of this mWorkerRefreshPolicy?

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@elega elega Sep 23, 2022

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updated guarded by

mWorkerInfoList.set(getAllWorkers());
}
return mWorkerInfoList.get();
}
return mWorkerInfoList;
}

/**
Expand Down