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[SPARK-23785][LAUNCHER] LauncherBackend doesn't check state of connection before setting state #20893

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[SPARK-23785][LAUNCHER] LauncherBackend doesn't check state of connection before setting state #20893

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[SPARK-23785][LAUNCHER] LauncherBackend doesn't check state of connec… 
…tion before setting state
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Sahil Takiar committed Mar 24, 2018
commit 4ca8a32e2a518f3c7ccecd406a8b03eac06f860b
6 changes: 3 additions & 3 deletions core/src/main/scala/org/apache/spark/launcher/LauncherBackend.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -67,13 +67,13 @@ private[spark] abstract class LauncherBackend {
}

def setAppId(appId: String): Unit = {
if (connection != null) {
if (connection != null && isConnected) {
connection.send(new SetAppId(appId))
}
}

def setState(state: SparkAppHandle.State): Unit = {
if (connection != null && lastState != state) {
if (connection != null && isConnected && lastState != state) {
connection.send(new SetState(state))
lastState = state
}
Expand Down Expand Up @@ -114,10 +114,10 @@ private[spark] abstract class LauncherBackend {

override def close(): Unit = {
try {
_isConnected = false
super.close()
} finally {
onDisconnected()
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@jiangxb1987 jiangxb1987 Mar 26, 2018

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I searched the code and seems this is a no-op?

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@sahilTakiar sahilTakiar Mar 26, 2018

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_isConnected is used in def isConnected(). Moving it from the finally block to before the call to super.close() avoids a race condition where a client tries to write to the connection after it has been closed.

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@jiangxb1987 jiangxb1987 Mar 27, 2018

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I know your meaning, but I'm not referring to isConnected, I mean onDisconnected seems not doing anything on Spark side.

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@jiangxb1987 jiangxb1987 Mar 27, 2018

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This is not quite directly related, but this should means it is safe to move _isConnected = false to before onDisconnected().

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@sahilTakiar sahilTakiar Mar 27, 2018

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Yeah, your right, it doesn't look like onDisconnected is being used anywhere, but its marked as protected so I guess its meant to be used by a sub-class (although no sub-class uses it).

So agree, this change should be safe, it doesn't change the semantics of any use of onDisconnected

_isConnected = false
}
}

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20 changes: 20 additions & 0 deletions launcher/src/test/java/org/apache/spark/launcher/LauncherServerSuite.java
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Expand Up @@ -185,6 +185,26 @@ public void testStreamFiltering() throws Exception {
}
}

@Test
public void testAppHandleDisconnect() throws Exception {
LauncherServer server = LauncherServer.getOrCreateServer();
ChildProcAppHandle handle = new ChildProcAppHandle(server);
String secret = server.registerHandle(handle);

TestClient client = null;
try {
Socket s = new Socket(InetAddress.getLoopbackAddress(), server.getPort());
client = new TestClient(s);
client.send(new Hello(secret, "1.4.0"));
handle.disconnect();
waitForError(client, secret);
} finally {
handle.kill();
close(client);
client.clientThread.join();
}
}

private void close(Closeable c) {
if (c != null) {
try {
Expand Down