Ahmed Hussein created HDFS-15679:
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Summary: DFSOutputStream close should be a no-op when called
multiple times
Key: HDFS-15679
URL: https://issues.apache.org/jira/browse/HDFS-15679
Project: Hadoop HDFS
Issue Type: Bug
Reporter: Ahmed Hussein
Assignee: Xiao Chen
While I was looking into the incorrect implementation of HDFS-15678, I found
that once I implement the correct logic, the Junit test fails.
It turns out that there is inconsistency in {{DFSOutputStream.closeImpl()}}
introduced by HDFS-13164.
The change in [that
line|https://github.com/apache/hadoop/commit/51088d323359587dca7831f74c9d065c2fccc60d#diff-3a80b95578dc5079cebf0441e1dab63d5844c02fa2d04071c165ec4f7029f918R860]
makes the close() throws exception multiple times which contradicts with
HDFS-5335.
Also, I believe the implementation is incorrect and it needs to be reviewed.
For example,
the implementation first checks {{isClosed()}} , then inside the {{finally
block}} (which is inside {{isClosed() block}}) , there is a second check for
{{!closed}}.
*A DFSOutputStream can never opened after being closed.*
{code:java}
if (isClosed()) {
LOG.debug("Closing an already closed stream. [Stream:{}, streamer:{}]",
closed, getStreamer().streamerClosed());
try {
getStreamer().getLastException().check(true);
} catch (IOException ioe) {
cleanupAndRethrowIOException(ioe);
} finally {
if (!closed) {
// If stream is not closed but streamer closed, clean up the stream.
// Most importantly, end the file lease.
closeThreads(true);
}
}
{code}
[~xiaochen] and [~yzhangal] can you please take another look at that patch?
That change breaks the semantic of {{close()}}. For convenience, this is a test
code that fails because of the change in HDFS-13164.
{code:java}
public void testCloseTwice() throws IOException {
DistributedFileSystem fs = cluster.getFileSystem();
FSDataOutputStream os = fs.create(new Path("/test"));
DFSOutputStream dos = (DFSOutputStream) Whitebox.getInternalState(os,
"wrappedStream");
DataStreamer streamer = (DataStreamer) Whitebox
.getInternalState(dos, "streamer");
@SuppressWarnings("unchecked")
LastExceptionInStreamer ex = (LastExceptionInStreamer) Whitebox
.getInternalState(streamer, "lastException");
Throwable thrown = (Throwable) Whitebox.getInternalState(ex, "thrown");
Assert.assertNull(thrown);
// force stream to break. output stream needs to encounter a real
// error to properly mark it closed with an exception
cluster.shutdown(true, false);
try {
dos.close();
Assert.fail("should have thrown");
} catch (IOException e) {
Assert.assertEquals(e.toString(), EOFException.class, e.getClass());
}
thrown = (Throwable) Whitebox.getInternalState(ex, "thrown");
Assert.assertNull(thrown);
dos.close();
// even if the exception is set again, close should not throw it
ex.set(new IOException("dummy"));
dos.close();
}
{code}
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