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slf4j over sysout not thread safe

I started using it to redirect all sysout and syserr to log files instead of catalina.out but its not thread safe as I started getting below exceptions. Solution was to patch the library and make LoggerAppenderImpl.appendAndLog and LoggerAppenderImpl.append methods synchronized for now as I am relying on assumption that we wont have too many system.out in third party libraries.


java.lang.StringIndexOutOfBoundsException: String index out of range: 117
at java.lang.String.(String.java:212)
at java.lang.StringBuilder.toString(StringBuilder.java:430)
at uk.org.lidalia.sysoutslf4j.context.LoggerAppenderImpl.flushBuffer(LoggerAppenderImpl.java:62)
at uk.org.lidalia.sysoutslf4j.context.LoggerAppenderImpl.appendAndLog(LoggerAppenderImpl.java:57)
at uk.org.lidalia.sysoutslf4j.system.SLF4JPrintStreamDelegate.appendAndLog(SLF4JPrintStreamDelegate.java:76)
at uk.org.lidalia.sysoutslf4j.system.SLF4JPrintStreamDelegate.delegatePrintln(SLF4JPrintStreamDelegate.java:56)
at uk.org.lidalia.sysoutslf4j.system.SLF4JPrintStreamImpl.println(SLF4JPrintStreamImpl.java:111)
at com.danga.MemCached.Logger.log(Logger.java:107)


and

java.lang.ArrayIndexOutOfBoundsException
at java.lang.String.getChars(String.java:855)
at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:391)
at java.lang.StringBuilder.append(StringBuilder.java:119)
at uk.org.lidalia.sysoutslf4j.context.LoggerAppenderImpl.appendAndLog(LoggerAppenderImpl.java:56)
at uk.org.lidalia.sysoutslf4j.system.SLF4JPrintStreamDelegate.appendAndLog(SLF4JPrintStreamDelegate.java:76)
at uk.org.lidalia.sysoutslf4j.system.SLF4JPrintStreamDelegate.delegatePrintln(SLF4JPrintStreamDelegate.java:56)
at uk.org.lidalia.sysoutslf4j.system.SLF4JPrintStreamImpl.println(SLF4JPrintStreamImpl.java:111)
at com.danga.MemCached.Logger.log(Logger.java:107)

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