Looks like a bug. Could you please enter a bug report? On 28/08/2011 4:39 PM, Odd Man wrote:

I've read that logback is thread safe, but I got exception using MDC. Is it bug or MDC access should be syncronized?

java.util.ConcurrentModificationException: null at java.util.HashMap$HashIterator.nextEntry(HashMap.java:793) ~[na:1.6.0_26] at java.util.HashMap$EntryIterator.next(HashMap.java:834) ~[na:1.6.0_26] at java.util.HashMap$EntryIterator.next(HashMap.java:832) ~[na:1.6.0_26] at java.util.HashMap.putAll(HashMap.java:523) ~[na:1.6.0_26] at ch.qos.logback.classic.util.LogbackMDCAdapter.duplicateAndInsertNewMap(LogbackMDCAdapter.java:69) ~[logback-classic-0.9.29.jar:na] at ch.qos.logback.classic.util.LogbackMDCAdapter.put(LogbackMDCAdapter.java:95) ~[logback-classic-0.9.29.jar:na] at org.slf4j.MDC.put(MDC.java:112) ~[slf4j-api-1.6.1.jar:1.6.1]

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