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https://issues.apache.org/jira/browse/HADOOP-7705?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13122681#comment-13122681
]
Steve Loughran commented on HADOOP-7705:
----------------------------------------
This patch is independent of the rest of the Hadoop codebase; it's a new logger
than can push out JSON content that is easy for management tools to parse
(indeed, the tests parse the data to verify round-tripping.
The test run shows what the output is, here are some examples from it
1. Simple log message, as it looks: one JSON node per line. All values
(escaped) strings except for time_t, which is a integer
{code}
{"name":"name","time":0,"level":"DEBUG","thread":"thread1","message":"hello,
world"}
{code}
2. Log with a single nested exception, reformatted as multiline for
readability. The exception class is added (if provided), and the stack is
included as an array.
{code}
{
"name":"testException",
"time":1317980185037,
"level":"INFO",
"thread":"quoted\"",
"message":"new line\n and {}",
"exceptionclass":"java.net.NoRouteToHostException",
"stack":[
"java.net.NoRouteToHostException: that box caught fire 3 years ago",
"\tat
org.apache.hadoop.log.TestLog4Json.testException(TestLog4Json.java:49)",
"\tat sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)",
"\tat
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)",
"\tat
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)",
"\tat java.lang.reflect.Method.invoke(Method.java:597)",
"\tat junit.framework.TestCase.runTest(TestCase.java:168)",
"\tat junit.framework.TestCase.runBare(TestCase.java:134)",
"\tat junit.framework.TestResult$1.protect(TestResult.java:110)",
"\tat junit.framework.TestResult.runProtected(TestResult.java:128)",
"\tat junit.framework.TestResult.run(TestResult.java:113)",
"\tat junit.framework.TestCase.run(TestCase.java:124)",
"\tat junit.framework.TestSuite.runTest(TestSuite.java:232)",
"\tat junit.framework.TestSuite.run(TestSuite.java:227)",
"\tat
org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:83)",
"\tat
org.apache.maven.surefire.junit4.JUnit4TestSet.execute(JUnit4TestSet.java:59)",
"\tat
org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.executeTestSet(AbstractDirectoryTestSuite.java:120)",
"\tat
org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.execute(AbstractDirectoryTestSuite.java:145)",
"\tat org.apache.maven.surefire.Surefire.run(Surefire.java:104)",
"\tat sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)",
"\tat
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)",
"\tat
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)",
"\tat java.lang.reflect.Method.invoke(Method.java:597)",
"\tat
org.apache.maven.surefire.booter.SurefireBooter.runSuitesInProcess(SurefireBooter.java:290)",
"\tat
org.apache.maven.surefire.booter.SurefireBooter.main(SurefireBooter.java:1017)"
]
}
{code}
One potential improvement would be to include the timestamp as a human readable
ISO time. The reason I haven't done this is the cost of creating this data -if
the target is a machine, it's not needed.
This log could be included as a (commented out) example in the conf/log4 file.
It must not go in the src/test log4 file as if there is a bug in the code, that
could break all tests.
> Add a log4j back end that can push out JSON data, one per line
> --------------------------------------------------------------
>
> Key: HADOOP-7705
> URL: https://issues.apache.org/jira/browse/HADOOP-7705
> Project: Hadoop Common
> Issue Type: New Feature
> Components: util
> Affects Versions: 0.23.0, 0.24.0
> Reporter: Steve Loughran
> Assignee: Steve Loughran
> Priority: Minor
> Attachments: HADOOP-7705-log4json.patch
>
>
> If we had a back end for Log4j that pushed out log events in single line JSON
> content, we'd have something that is fairly straightforward to machine parse.
> If: it may be harder to do than expected. Once working HADOOP-6244 could use
> it.
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