Fix TraceFileObserver NPE when trace file already exists#6891
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bentsherman merged 4 commits intomasterfrom Mar 17, 2026
Merged
Fix TraceFileObserver NPE when trace file already exists#6891bentsherman merged 4 commits intomasterfrom
bentsherman merged 4 commits intomasterfrom
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When TraceHelper.newFileWriter() throws in onFlowCreate() (e.g. trace file already exists on S3 without overwrite enabled), the writer Agent is left null. Every subsequent onTaskComplete, onTaskCached, and onFlowComplete call then throws a NullPointerException, spamming the log with stack traces for every task in the run. Catch the exception in onFlowCreate and log at warn level so the user sees the actionable message, return early, and add null-safe guards on writer at the remaining call sites so the observer degrades gracefully. Closes #6890 Signed-off-by: Rob Syme <rob.syme@gmail.com>
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pditommaso
reviewed
Mar 5, 2026
…ver.groovy Co-authored-by: Paolo Di Tommaso <paolo.ditommaso@gmail.com> Signed-off-by: Robert Syme <rob.syme@gmail.com>
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Summary
NullPointerExceptionspam inTraceFileObserverwhen trace file already exists andoverwriteis not enabledlog.warnso users see the actionable "enable trace.overwrite" message instead of silent failureCloses #6890
Problem
When
TraceHelper.newFileWriter()throws inonFlowCreate()(e.g. trace file already exists on S3), thewriterAgent is never initialized. Every subsequent call toonTaskComplete(),onTaskCached(), andonFlowComplete()then throws:The original
AbortOperationExceptionwith the helpful user-facing message is swallowed atlog.debugbySession.notifyEvent(), so users never see why their trace file wasn't written.Changes
TraceFileObserver.groovy:onFlowCreate()with try-catch; log atwarnlevel (user-visible) anddebuglevel (full stack trace), then return early?.null-safe guards onwriterinonFlowComplete(),onTaskComplete(),onTaskCached()traceFileaccess inonFlowComplete()withif( traceFile )TraceFileObserverTest.groovy:'should degrade gracefully when trace file already exists'— verifies that when file creation fails, all task events and flow completion proceed without exceptions, and the original file is untouched