[
https://issues.apache.org/jira/browse/HDFS-10986?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Mingliang Liu updated HDFS-10986:
---------------------------------
Description:
There are some subcommands in {{DFSAdmin}} that swallow IOException and give
very limited error message, if any, to the stderr.
{code}
$ hdfs dfsadmin -getBalancerBandwidth 127.0.0.1:9866
Datanode unreachable.
$ hdfs dfsadmin -getDatanodeInfo localhost:9866
Datanode unreachable.
$ hdfs dfsadmin -evictWriters 127.0.0.1:9866
$ echo $?
-1
{code}
User is not able to get the exception stack even the LOG level is DEBUG. This
is not very user friendly. Fortunately, if the port number is not accessible
(say 9999), users can infer the detailed error message by IPC logs:
{code}
$ hdfs dfsadmin -getBalancerBandwidth 127.0.0.1:9999
2016-10-07 18:01:35,115 WARN util.NativeCodeLoader: Unable to load
native-hadoop library for your platform... using builtin-java classes where
applicable
2016-10-07 18:01:36,335 INFO ipc.Client: Retrying connect to server:
localhost/127.0.0.1:9999. Already tried 0 time(s); retry policy is
RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
.....
2016-10-07 18:01:45,361 INFO ipc.Client: Retrying connect to server:
localhost/127.0.0.1:9999. Already tried 9 time(s); retry policy is
RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
2016-10-07 18:01:45,362 WARN ipc.Client: Failed to connect to server:
localhost/127.0.0.1:9999: retries get failed due to exceeded maximum allowed
retries number: 10
java.net.ConnectException: Connection refused
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at
sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
...
at org.apache.hadoop.hdfs.tools.DFSAdmin.run(DFSAdmin.java:2073)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:76)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:90)
at org.apache.hadoop.hdfs.tools.DFSAdmin.main(DFSAdmin.java:2225)
Datanode unreachable.
{code}
We should fix this by providing detailed error message. Actually, the
{{DFSAdmin#run}} already handles exception carefully, including:
# set the exit ret value to -1
# print the error message
# log the exception stack trace (in DEBUG level)
All we need to do is to not swallow exceptions without good reason.
was:
There are some subcommands in {{DFSAdmin}} that swallow IOException and give
very limited error message, if any, to the stderr.
{code}
$ hdfs dfsadmin -getBalancerBandwidth 127.0.0.1:9866
Datanode unreachable.
$ hdfs dfsadmin -getDatanodeInfo localhost:9866
Datanode unreachable.
$ hdfs dfsadmin -evictWriters 127.0.0.1:9866
$ echo $?
-1
{code}
User is not able to get the exception stack even the LOG level is DEBUG. This
is not very user friendly. Fortunately, if the port number is not accessible
(say 9999), users can infer the detailed error message by IPC logs:
{code}
$ hdfs dfsadmin -getBalancerBandwidth 127.0.0.1:9999
2016-10-07 18:01:35,115 WARN util.NativeCodeLoader: Unable to load
native-hadoop library for your platform... using builtin-java classes where
applicable
2016-10-07 18:01:36,335 INFO ipc.Client: Retrying connect to server:
localhost/127.0.0.1:9690. Already tried 0 time(s); retry policy is
RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
.....
2016-10-07 18:01:45,361 INFO ipc.Client: Retrying connect to server:
localhost/127.0.0.1:9690. Already tried 9 time(s); retry policy is
RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
2016-10-07 18:01:45,362 WARN ipc.Client: Failed to connect to server:
localhost/127.0.0.1:9690: retries get failed due to exceeded maximum allowed
retries number: 10
java.net.ConnectException: Connection refused
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at
sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
...
at org.apache.hadoop.hdfs.tools.DFSAdmin.run(DFSAdmin.java:2073)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:76)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:90)
at org.apache.hadoop.hdfs.tools.DFSAdmin.main(DFSAdmin.java:2225)
Datanode unreachable.
{code}
We should fix this by providing detailed error message. Actually, the
{{DFSAdmin#run}} already handles exception carefully, including:
# set the exit ret value to -1
# print the error message
# log the exception stack trace (in DEBUG level)
All we need to do is to not swallow exceptions without good reason.
> DFSAdmin should log detailed error message if any
> -------------------------------------------------
>
> Key: HDFS-10986
> URL: https://issues.apache.org/jira/browse/HDFS-10986
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: tools
> Reporter: Mingliang Liu
> Assignee: Mingliang Liu
> Attachments: HDFS-10986.000.patch
>
>
> There are some subcommands in {{DFSAdmin}} that swallow IOException and give
> very limited error message, if any, to the stderr.
> {code}
> $ hdfs dfsadmin -getBalancerBandwidth 127.0.0.1:9866
> Datanode unreachable.
> $ hdfs dfsadmin -getDatanodeInfo localhost:9866
> Datanode unreachable.
> $ hdfs dfsadmin -evictWriters 127.0.0.1:9866
> $ echo $?
> -1
> {code}
> User is not able to get the exception stack even the LOG level is DEBUG. This
> is not very user friendly. Fortunately, if the port number is not accessible
> (say 9999), users can infer the detailed error message by IPC logs:
> {code}
> $ hdfs dfsadmin -getBalancerBandwidth 127.0.0.1:9999
> 2016-10-07 18:01:35,115 WARN util.NativeCodeLoader: Unable to load
> native-hadoop library for your platform... using builtin-java classes where
> applicable
> 2016-10-07 18:01:36,335 INFO ipc.Client: Retrying connect to server:
> localhost/127.0.0.1:9999. Already tried 0 time(s); retry policy is
> RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000
> MILLISECONDS)
> .....
> 2016-10-07 18:01:45,361 INFO ipc.Client: Retrying connect to server:
> localhost/127.0.0.1:9999. Already tried 9 time(s); retry policy is
> RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000
> MILLISECONDS)
> 2016-10-07 18:01:45,362 WARN ipc.Client: Failed to connect to server:
> localhost/127.0.0.1:9999: retries get failed due to exceeded maximum allowed
> retries number: 10
> java.net.ConnectException: Connection refused
> at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
> at
> sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
> ...
> at org.apache.hadoop.hdfs.tools.DFSAdmin.run(DFSAdmin.java:2073)
> at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:76)
> at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:90)
> at org.apache.hadoop.hdfs.tools.DFSAdmin.main(DFSAdmin.java:2225)
> Datanode unreachable.
> {code}
> We should fix this by providing detailed error message. Actually, the
> {{DFSAdmin#run}} already handles exception carefully, including:
> # set the exit ret value to -1
> # print the error message
> # log the exception stack trace (in DEBUG level)
> All we need to do is to not swallow exceptions without good reason.
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