liying created HDFS-14737:
-----------------------------

             Summary: Writing data through the HDFS nfs3 service is very slow, 
and timeout occurs while mount directories on the nfs client
                 Key: HDFS-14737
                 URL: https://issues.apache.org/jira/browse/HDFS-14737
             Project: Hadoop HDFS
          Issue Type: Improvement
    Affects Versions: 2.7.2
            Reporter: liying
            Assignee: liying


We know the NFS Gateway supports NFSv3 and allows HDFS to be mounted as part of 
the client’s local file system.  I start the portmap and nfs3server in the 
hadoop node,and use the command (mount -t nfs -o vers=3,proto=tcp,nolock 
nfs3serverIP:/ /hdfs) to mount. It works well。Then i ues this command to mount 
on many client. And i used linux cp to copy files to the mounted 
dir(/hdfs),found the speed was very slow . There is a lot of information in the 
log as the follow:

2019-08-14 15:36:28,347 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:37:03,093 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:37:03,850 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:37:14,780 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:37:14,928 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:37:28,410 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:38:09,310 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:38:10,069 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:38:14,856 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:38:14,957 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:38:28,475 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:39:14,923 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:39:14,987 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:39:15,541 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:39:16,287 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:39:28,530 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:40:15,015 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:40:15,024 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:40:15,028 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:40:21,757 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:40:22,508 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:40:28,583 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:41:15,063 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:41:15,086 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:41:27,983 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:41:28,647 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:41:28,729 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:42:15,184 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:42:15,191 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332
2019-08-14 15:42:28,707 INFO org.apache.hadoop.security.ShellBasedIdMapping: 
Can't map group supergroup. Use its string hashcode:-1710818332

Then i print the jstack log to check the threads of nfs3server, and found some 
threads' status are waiting for monitor entry : BLOCKED(on object monitor). 
After checking the codes, I found that the updateMapIncr will be invoked every 
time if the group or user doesn't exits. And In the class ShellBasedIdMapping, 
many methods are made with synchronized. So i think we can avoid to invoke the 
updateMapIncr every time.

 

 



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