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https://issues.apache.org/jira/browse/NIFI-1856?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15772949#comment-15772949
]
ASF GitHub Bot commented on NIFI-1856:
--------------------------------------
Github user jackowaya commented on a diff in the pull request:
https://github.com/apache/nifi/pull/1355#discussion_r93767588
--- Diff:
nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/ExecuteStreamCommand.java
---
@@ -186,7 +195,15 @@ public ValidationResult validate(String subject,
String input, ValidationContext
.addValidator(StandardValidators.createDirectoryExistsValidator(true, true))
.required(false)
.build();
-
+ static final PropertyDescriptor REDIRECT_ERROR = new
PropertyDescriptor.Builder()
+ .name("Redirect Error Stream")
+ .description("where shoud the error stream from external
process get redirected"
+ + "\n1) log - outputs to the nifi logger"
+ + "\n2) output stream - redirects to the output stream
relation"
+ + "\n3) error stream - redirects to the error stream
relation")
+ .allowableValues("log", "output stream","error stream")
--- End diff --
It would be better to hold these strings in static final variables so they
can be reused later without fear of mistyping.
Also spacing looks off here. You should run autoformat again.
> ExecuteStreamCommand Needs to Consume Standard Error
> ----------------------------------------------------
>
> Key: NIFI-1856
> URL: https://issues.apache.org/jira/browse/NIFI-1856
> Project: Apache NiFi
> Issue Type: Bug
> Reporter: Alan Jackoway
> Assignee: Karthik Narayanan
>
> I was using ExecuteStreamProcess to run certain hdfs commands that are tricky
> to write in nifi but easy in bash (e.g. {{hadoop fs -rm -r
> /data/*/2014/05/05}})
> However, my larger commands kept hanging even though when I run them from the
> command line they finish quickly.
> Based on
> http://www.javaworld.com/article/2071275/core-java/when-runtime-exec---won-t.html
> I believe that ExecuteStreamCommand and possibly other processors need to
> consume the standard error stream to prevent the processes from blocking when
> standard error gets filled.
> To reproduce. Create this as ~/write.py
> {code:python}
> import sys
> count = int(sys.argv[1])
> for x in range(count):
> sys.stderr.write("ERROR %d\n" % x)
> sys.stdout.write("OUTPUT %d\n" % x)
> {code}
> Create a flow that goes
> # GenerateFlowFile - 5 minutes schedule 0 bytes size
> # ExecuteStreamCommand - Command arguments /Users/alanj/write.py;100 Command
> Path python
> # PutFile - /tmp/write/
> routing output stream of ExecuteStreamCommand to PutFile
> When you turn everything on, you get 100 lines (not 200) of just the standard
> output in /tmp/write.
> Next, change the command arguments to /Users/alanj/write.py;100000 and turn
> everything on again. The command will hang.
> I believe that whenever you execute a process the way ExecuteStreamCommand is
> doing, you need to consume the standard error stream to keep it from
> blocking. This may also affect things like ExecuteProcess and ExecuteScript
> as well.
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