/// <summary>
/// To ensure there are not multiple instances of the SCM running on a given
/// cluster, a global pid file is used.
/// </summary>
/// <remarks>
/// To ensure there are not multiple instances of the SCM running on a given
/// cluster, a global pid file is used. This file contains the hostname of the
/// machine that owns the pid file.
/// </remarks>
/// <returns>true if the pid file was written, false otherwise</returns>
/// <exception cref="Org.Apache.Hadoop.Yarn.Exceptions.YarnException"/>
private bool WriteGlobalCleanerPidFile()
{
string root = conf.Get(YarnConfiguration.SharedCacheRoot, YarnConfiguration.DefaultSharedCacheRoot
);
Path pidPath = new Path(root, GlobalCleanerPid);
try
{
FileSystem fs = FileSystem.Get(this.conf);
if (fs.Exists(pidPath))
{
return(false);
}
FSDataOutputStream os = fs.Create(pidPath, false);
// write the hostname and the process id in the global cleaner pid file
string Id = ManagementFactory.GetRuntimeMXBean().GetName();
os.WriteUTF(Id);
os.Close();
// add it to the delete-on-exit to ensure it gets deleted when the JVM
// exits
fs.DeleteOnExit(pidPath);
}
catch (IOException e)
{
throw new YarnException(e);
}
Log.Info("Created the global cleaner pid file at " + pidPath.ToString());
return(true);
}