Github user witgo commented on a diff in the pull request:
https://github.com/apache/spark/pull/1609#discussion_r15447449
--- Diff:
core/src/main/scala/org/apache/spark/storage/BlockObjectWriter.scala ---
@@ -107,68 +109,296 @@ private[spark] class DiskBlockObjectWriter(
private var fos: FileOutputStream = null
private var ts: TimeTrackingOutputStream = null
private var objOut: SerializationStream = null
+
+ // Did we create this file or was it already present : used in revert to
decide
+ // if we should delete this file or not. Also used to detect if file was
deleted
+ // between creation of BOW and its actual init
+ private val initiallyExists = file.exists() && file.isFile
private val initialPosition = file.length()
private var lastValidPosition = initialPosition
+
private var initialized = false
+ // closed explicitly ?
+ private var closed = false
+ // Attempt to cleanly close ? (could also be closed via revert)
+ // Note, a cleanly closed file could be subsequently reverted
+ private var cleanCloseAttempted = false
+ // Was the file actually opened atleast once.
+ // Note: initialized/streams change state with close/revert.
+ private var wasOpenedOnce = false
private var _timeWriting = 0L
- override def open(): BlockObjectWriter = {
- fos = new FileOutputStream(file, true)
- ts = new TimeTrackingOutputStream(fos)
- channel = fos.getChannel()
+ // Due to some directory creation race issues in spark, it has been
observed that
+ // sometimes file creation happens 'before' the actual directory has
been created
+ // So we attempt to retry atleast once with a mkdirs in case directory
was missing.
+ private def init() {
+ init(canRetry = true)
+ }
+
+ private def init(canRetry: Boolean) {
+
+ if (closed) throw new IOException("Already closed")
+
+ assert (! initialized)
+ assert (! wasOpenedOnce)
+ var exists = false
+ try {
+ exists = file.exists()
+ if (! exists && initiallyExists && 0 != initialPosition && !
Utils.inShutdown) {
+ // Was deleted by cleanup thread ?
+ throw new IOException("file " + file + " cleaned up ? exists = " +
exists +
+ ", initiallyExists = " + initiallyExists + ", initialPosition =
" + initialPosition)
+ }
+ fos = new FileOutputStream(file, true)
+ } catch {
+ case fEx: FileNotFoundException =>
+ // There seems to be some race in directory creation.
+ // Attempts to fix it dont seem to have worked : working around
the problem for now.
+ logDebug("Unable to open " + file + ", canRetry = " + canRetry +
", exists = " + exists +
+ ", initialPosition = " + initialPosition + ", in shutdown = " +
Utils.inShutdown(), fEx)
+ if (canRetry && ! Utils.inShutdown()) {
+ // try creating the parent directory if that is the issue.
+ // Since there can be race with others, dont bother checking for
+ // success/failure - the call to init() will resolve if fos can
be created.
+ file.getParentFile.mkdirs()
+ // Note, if directory did not exist, then file does not either -
and so
+ // initialPosition would be zero in either case.
+ init(canRetry = false)
+ return
+ } else throw fEx
+ }
+
+ try {
+ // This is to workaround case where creation of object and actual
init
+ // (which can happen much later) happens after a delay and the
cleanup thread
+ // cleaned up the file.
+ channel = fos.getChannel
+ val fosPos = channel.position()
+ if (initialPosition != fosPos) {
+ throw new IOException("file cleaned up ? " + file.exists() +
+ ", initialpos = " + initialPosition +
+ "current len = " + fosPos + ", in shutdown ? " +
Utils.inShutdown)
+ }
+
+ ts = new TimeTrackingOutputStream(fos)
+ val bos = new BufferedOutputStream(ts, bufferSize)
+ bs = compressStream(bos)
+ objOut = serializer.newInstance().serializeStream(bs)
+ initialized = true
+ wasOpenedOnce = true;
+ } finally {
+ if (! initialized) {
+ // failed, cleanup state.
+ val tfos = fos
+ updateCloseState()
+ tfos.close()
+ }
+ }
+ }
+
+ private def open(): BlockObjectWriter = {
+ init()
lastValidPosition = initialPosition
- bs = compressStream(new BufferedOutputStream(ts, bufferSize))
- objOut = serializer.newInstance().serializeStream(bs)
- initialized = true
this
}
- override def close() {
- if (initialized) {
- if (syncWrites) {
- // Force outstanding writes to disk and track how long it takes
- objOut.flush()
+ private def updateCloseState() {
+
+ if (ts ne null) _timeWriting += ts.timeWriting
+
+ bs = null
+ channel = null
+ fos = null
+ ts = null
+ objOut = null
+ initialized = false
+ }
+
+ private def flushAll() {
+ if (closed) throw new IOException("Already closed")
+
+ // NOTE: Because Kryo doesn't flush the underlying stream we
explicitly flush both the
+ // serializer stream and the lower level stream.
+ if (objOut ne null) {
+ objOut.flush()
+ bs.flush()
+ }
+ }
+
+ private def closeAll(needFlush: Boolean, needRevert: Boolean) {
+
+ if (null != objOut) {
+ val truncatePos = if (needRevert) initialPosition else -1L
+ assert (! this.closed)
+
+ // In case syncWrites is true or we need to truncate
+ var cleanlyClosed = false
+ try {
+ // Flushing if we need to truncate also. Currently, we reopen to
truncate
+ // so this is not strictly required (since close could write
further to streams).
+ // Keeping it around in case that gets relaxed.
+ if (needFlush || needRevert) flushAll()
+
val start = System.nanoTime()
- fos.getFD.sync()
+ try {
+ if (syncWrites) {
+ // Force outstanding writes to disk and track how long it takes
+ fos.getFD.sync()
+ }
+ } catch {
+ case sfe: SyncFailedException => // ignore
+ }
+ // must cause cascading close. Note, repeated close on closed
streams should not cause
+ // issues : except some libraries do not honour it - hence not
explicitly closing bs/fos
+ objOut.close()
+ // bs.close()
+ // fos.close()
_timeWriting += System.nanoTime() - start
- }
- objOut.close()
- _timeWriting += ts.timeWriting
+ // fos MUST have been closed.
+ assert((channel eq null) || !channel.isOpen)
+ cleanlyClosed = true
+
+ } finally {
+
+ this.closed = true
+ if (! cleanlyClosed) {
+ // could not cleanly close. We have two cases here -
+ // a) normal close,
+ // b) revert
+ // If (a) then then streams/data is in inconsistent so we cant
really recover
+ // simply release fd and allow exception to bubble up.
+ // If (b) and file length >= initialPosition, then truncate file
and ignore exception
+ // else,cause exception to bubble up since we cant recover
+ assert (fos ne null)
+ try { fos.close() } catch { case ioEx: IOException => /* best
case attempt, ignore */ }
+ }
+
+ updateCloseState()
+
+ // Since close can end up writing data in general case (inspite of
flush),
+ // we reopen to truncate file.
+ if (needRevert) {
+ // remove if not earlier existed : best case effort so we dont
care about return value
+ // of delete (it can fail if file was already deleted by cleaner
threads for example)
+ if (! initiallyExists) {
+ file.delete()
+ // Explicitly ignore exceptions (when cleanlyClosed = false)
and return
+ // from here. Usually not good idea in finally, but it is ok
here.
+ return
+ } else {
+ val fileLen = file.length()
+ if (fileLen >= truncatePos) {
+ if (fileLen > truncatePos)
DiskBlockObjectWriter.truncateIfExists(file, truncatePos)
- channel = null
- bs = null
- fos = null
- ts = null
- objOut = null
- initialized = false
+ // Validate length.
+ assert(truncatePos == file.length() || Utils.inShutdown(),
+ "truncatePos = " + truncatePos + ", len = " +
file.length() +
+ ", in shutdown = " + Utils.inShutdown())
+
+ // Explicitly ignore exceptions (when cleanlyClosed = false)
and return
+ // from here. Usually not good idea in finally, but it is ok
here.
+ return
+ } // else cause the exception to bubble up if thrown
+ }
+ }
+ }
+ } else {
+ // it is possible for open to have never been called - no data
written to this
+ // partition for example. so objOut == null
+ this.closed = true
}
+ initialized = false
}
- override def isOpen: Boolean = objOut != null
+ private def validateBytesWritten() {
+ // This should happen due to file deletion, during cleanup. Ensure
bytesWritten is in sane
+ // state. Note, parallel threads continue to run while shutdown
threads are running : so
+ // this prevents unwanted assertion failures and exception elsewhere.
+ if (lastValidPosition < initialPosition) {
+ // This is invoked so that assertions within bytes written are
validated.
+ assert (bytesWritten >= 0)
+ lastValidPosition = initialPosition
+ }
+ }
- override def commit(): Long = {
+ override def commitAndClose() {
if (initialized) {
- // NOTE: Because Kryo doesn't flush the underlying stream we
explicitly flush both the
- // serializer stream and the lower level stream.
- objOut.flush()
- bs.flush()
+ // opened, file still open
+ assert (wasOpenedOnce)
+ // Note, set cleanCloseAttempted even before we finish the close :
so that a revert on this
+ // in case close fails can truncate to previous state !
+ cleanCloseAttempted = true
+ closeAll(needFlush = true, needRevert = false)
+
val prevPos = lastValidPosition
- lastValidPosition = channel.position()
- lastValidPosition - prevPos
+ assert (prevPos == initialPosition)
+ assert (null == fos)
+
+ lastValidPosition = file.length()
+ validateBytesWritten()
+ // review: remove ?
+ assert (bytesWritten >= 0, "bytesWritten = " + bytesWritten +
+ ", initial pos = " + initialPosition + ", last valid pos = " +
lastValidPosition)
+
+ } else if (cleanCloseAttempted) {
+ // opened and closed cleanly
+ assert (closed)
+ assert (wasOpenedOnce)
+ // size should be lastValidPosition, or file deleted due to shutdown.
+ assert (lastValidPosition == file.length() || Utils.inShutdown,
+ "lastValidPosition = " + lastValidPosition +
+ ", file len = " + file.length() + ", exists = " + file.exists())
+
} else {
- // lastValidPosition is zero if stream is uninitialized
- lastValidPosition
+ // reverted or never opened.
+ this.closed = true
+ assert (initialPosition == file.length() || (0 == initialPosition &&
! initiallyExists) ||
+ Utils.inShutdown, "initialPosition = " + initialPosition +
+ ", file len = " + file.length() + ", exists = " + file.exists())
+ assert(lastValidPosition == initialPosition)
}
}
- override def revertPartialWrites() {
+ override def revertPartialWritesAndClose() {
if (initialized) {
- // Discard current writes. We do this by flushing the outstanding
writes and
- // truncate the file to the last valid position.
- objOut.flush()
- bs.flush()
- channel.truncate(lastValidPosition)
+ // opened, file still open
+ // Discard current writes. We do this by truncating the file to the
last valid position.
+ closeAll(needFlush = true, needRevert = true)
+ validateBytesWritten()
+ assert (bytesWritten == 0, "bytesWritten = " + bytesWritten +
+ ", initial pos = " + initialPosition + ", last valid pos = " +
lastValidPosition)
+ assert (initialPosition == file.length() || Utils.inShutdown,
+ "initialPosition = " + initialPosition +
+ ", file len = " + file.length() + ", exists = " + file.exists())
+ } else if (cleanCloseAttempted) {
+ // Already opened and closed : truncate to last location (or delete
+ // if created in this instance)
+ assert (closed)
+ cleanCloseAttempted = false
+
+ // truncate to initialPosition
+ // remove if not earlier existed
+ if (! initiallyExists) {
--- End diff --
Same as above.
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