Vikas Vishwakarma created HBASE-18517:
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             Summary: limit max log message width in log4j
                 Key: HBASE-18517
                 URL: https://issues.apache.org/jira/browse/HBASE-18517
             Project: HBase
          Issue Type: Bug
            Reporter: Vikas Vishwakarma
            Assignee: Vikas Vishwakarma


We had two cases now in our prod / pilot setups which is leading to humongous 
log lines in RegionServer logs. 
In one case one of the phoenix user had constructed a query with a really large 
list of Id filters (61 MB) that translated into HBase scan that was running 
slow which lead to responseTooSlow messages in the logs with the entire filter 
list being printed in the logs, example
ipc.RpcServer - (responseTooSlow): 
{"call":"Scan(org.apache.hadoop.hbase.protobuf.generated.ClientProtos$ScanRequest)","starttimems":1501457864417,"responsesize":11,"method":"Scan","param":"region
 { type: REGION_NAME value:  ..... 
org.apache.hadoop.hbase.filter.FirstKeyOnlyFilter\\022\351\\200\\036\\n(org.apache.phoenix.filter.SkipScanFilter
 ... <a really long filter list leading to single log lines of size 61MB> ... 

There was another case where a use case had created a table with really large 
key/region names. This was causing humongous log lines for flush and compaction 
on these regions filling up the RS logs

These large logs usually cause issues with disk I/O load, loading the splunk 
servers, even machine perf degradations. With 61 MB log lines basic log 
processing commands like vim, scrolling the logs, wc -l , etc were getting 
stuck. High GC activity was also noted on this cluster although not 100% sure 
if it was related to above issue. 

We should consider limiting the message size in logs which can be easily done 
by adding a maximum width format modifier on the message conversion character 
in log4j.properties
log4j.appender.console.layout.ConversionPattern=%d{ISO8601} %-5p [%t] %c{2}: 
%m%n
to 
log4j.appender.console.layout.ConversionPattern=%d{ISO8601} %-5p [%t] %c{2}: 
%.10000m%n




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