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HBASE-28146: Make ServerManager rsAdmins map thread safe #5461

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merged 5 commits into from
Oct 23, 2023
Merged

HBASE-28146: Make ServerManager rsAdmins map thread safe #5461

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f5d018b
Make ServerManager rsAdmins map thread safe
Oct 11, 2023
a7f590c
use computeIfAbsent, use ConcurrentMap declaration
Oct 12, 2023
0d15ff5
don't use computeIfAbsent
Oct 12, 2023
c32e103
rm rsAdmins cache
Oct 18, 2023
9e71dd3
improve log format
Oct 20, 2023
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27 changes: 17 additions & 10 deletions hbase-server/src/main/java/org/apache/hadoop/hbase/master/ServerManager.java
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Original file line number Diff line number Diff line change
Expand Up @@ -23,12 +23,13 @@
import java.net.InetAddress;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentNavigableMap;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.CopyOnWriteArrayList;
Expand Down Expand Up @@ -128,7 +129,8 @@ public class ServerManager {
* Map of admin interfaces per registered regionserver; these interfaces we use to control
* regionservers out on the cluster
*/
private final Map<ServerName, AdminService.BlockingInterface> rsAdmins = new HashMap<>();
private final ConcurrentMap<ServerName, AdminService.BlockingInterface> rsAdmins =
new ConcurrentHashMap<>();

/** List of region servers that should not get any more new regions. */
private final ArrayList<ServerName> drainingServers = new ArrayList<>();
Expand Down Expand Up @@ -718,14 +720,19 @@ public static void closeRegionSilentlyAndWait(ClusterConnection connection, Serv
public AdminService.BlockingInterface getRsAdmin(final ServerName sn) throws IOException {
AdminService.BlockingInterface admin = this.rsAdmins.get(sn);
if (admin == null) {
LOG.debug("New admin connection to " + sn.toString());
if (sn.equals(master.getServerName()) && master instanceof HRegionServer) {
// A master is also a region server now, see HBASE-10569 for details
admin = ((HRegionServer) master).getRSRpcServices();
} else {
admin = this.connection.getAdmin(sn);
}
this.rsAdmins.put(sn, admin);
return this.rsAdmins.computeIfAbsent(sn, server -> {
LOG.debug("New admin connection to " + server.toString());
if (server.equals(master.getServerName()) && master instanceof HRegionServer) {
// A master is also a region server now, see HBASE-10569 for details
return ((HRegionServer) master).getRSRpcServices();
} else {
try {
return this.connection.getAdmin(server);
} catch (IOException e) {
throw new RuntimeException(e);
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We should throw this IOException out? This is a problem of computeIfAbsent, as the functional interface does not throw IOException...

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Yeah, good point

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As written, it seems we need some synchronization. A concurrent map is pointless if you do unsyncrhonized writes on it. You could use ConcurrentMapUtils.computeIfAbsentEx to get around the exception issue.

That said, looking at the impls of getRSRpcServices and getAdmin, I don't think we really need to cache these at all. getRSRpcServices directly returns an instance variable. getAdmin already does it's own caching.

So it might make sense to simply remove the rsAdmins map. @Apache9 what do you think?

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computeIfAbsentEx seems like a good idea here. I don't have an informed opinion regarding whether the caching is really necessary, but I'm happy to rip it out if we think that's worth doing now

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Ah, checked the code, as @bbeaudreault mentioned, we already have a cache in ConnectionImplementation,

hbase/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionImplementation.java

Line 1434 in 18a38ae

return (AdminProtos.AdminService.BlockingInterface) computeIfAbsentEx(stubs, key, () -> {

So I think we can just remove the cache here.

}
}
});
}
return admin;
}
Expand Down