/// <exception cref="System.Exception"/>
/// <exception cref="System.IO.IOException"/>
private void DoCheckpoint()
{
System.Diagnostics.Debug.Assert(canceler != null);
long txid;
NNStorage.NameNodeFile imageType;
// Acquire cpLock to make sure no one is modifying the name system.
// It does not need the full namesystem write lock, since the only thing
// that modifies namesystem on standby node is edit log replaying.
namesystem.CpLockInterruptibly();
try
{
System.Diagnostics.Debug.Assert(namesystem.GetEditLog().IsOpenForRead(), "Standby Checkpointer should only attempt a checkpoint when "
+ "NN is in standby mode, but the edit logs are in an unexpected state");
FSImage img = namesystem.GetFSImage();
long prevCheckpointTxId = img.GetStorage().GetMostRecentCheckpointTxId();
long thisCheckpointTxId = img.GetLastAppliedOrWrittenTxId();
System.Diagnostics.Debug.Assert(thisCheckpointTxId >= prevCheckpointTxId);
if (thisCheckpointTxId == prevCheckpointTxId)
{
Log.Info("A checkpoint was triggered but the Standby Node has not " + "received any transactions since the last checkpoint at txid "
+ thisCheckpointTxId + ". Skipping...");
return;
}
if (namesystem.IsRollingUpgrade() && !namesystem.GetFSImage().HasRollbackFSImage(
))
{
// if we will do rolling upgrade but have not created the rollback image
// yet, name this checkpoint as fsimage_rollback
imageType = NNStorage.NameNodeFile.ImageRollback;
}
else
{
imageType = NNStorage.NameNodeFile.Image;
}
img.SaveNamespace(namesystem, imageType, canceler);
txid = img.GetStorage().GetMostRecentCheckpointTxId();
System.Diagnostics.Debug.Assert(txid == thisCheckpointTxId, "expected to save checkpoint at txid="
+ thisCheckpointTxId + " but instead saved at txid=" + txid);
// Save the legacy OIV image, if the output dir is defined.
string outputDir = checkpointConf.GetLegacyOivImageDir();
if (outputDir != null && !outputDir.IsEmpty())
{
img.SaveLegacyOIVImage(namesystem, outputDir, canceler);
}
}
finally
{
namesystem.CpUnlock();
}
// Upload the saved checkpoint back to the active
// Do this in a separate thread to avoid blocking transition to active
// See HDFS-4816
ExecutorService executor = Executors.NewSingleThreadExecutor(uploadThreadFactory);
Future <Void> upload = executor.Submit(new _Callable_204(this, imageType, txid));
executor.Shutdown();
try
{
upload.Get();
}
catch (Exception e)
{
// The background thread may be blocked waiting in the throttler, so
// interrupt it.
upload.Cancel(true);
throw;
}
catch (ExecutionException e)
{
throw new IOException("Exception during image upload: " + e.Message, e.InnerException
);
}
}