{"record":{"id":"1b06c5d901c1b4f8","repo":"prometheus/node_exporter","slug":"error-reading-task-for-pid-d-w","errorCode":null,"errorMessage":"error reading task for pid %d: %w","messagePattern":"error reading task for pid (.+?): %w","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"collector/processes_linux.go","lineNumber":156,"sourceCode":"\t\tprocStates[stat.State]++\n\t\tthread += stat.NumThreads\n\t\terr = c.getThreadStates(pid.PID, stat, threadStates)\n\t\tif err != nil {\n\t\t\treturn 0, nil, 0, nil, err\n\t\t}\n\t}\n\treturn pids, procStates, thread, threadStates, nil\n}\n\nfunc (c *processCollector) getThreadStates(pid int, pidStat procfs.ProcStat, threadStates map[string]int32) error {\n\tfs, err := procfs.NewFS(procFilePath(path.Join(strconv.Itoa(pid), \"task\")))\n\tif err != nil {\n\t\tif c.isIgnoredError(err) {\n\t\t\tc.logger.Debug(\"file not found when retrieving tasks for pid\", \"pid\", pid, \"err\", err)\n\t\t\treturn nil\n\t\t}\n\t\tc.logger.Debug(\"error reading tasks for pid\", \"pid\", pid, \"err\", err)\n\t\treturn fmt.Errorf(\"error reading task for pid %d: %w\", pid, err)\n\t}\n\n\tt, err := fs.AllProcs()\n\tif err != nil {\n\t\tif c.isIgnoredError(err) {\n\t\t\tc.logger.Debug(\"file not found when retrieving tasks for pid\", \"pid\", pid, \"err\", err)\n\t\t\treturn nil\n\t\t}\n\t\treturn fmt.Errorf(\"unable to list all threads for pid: %d %w\", pid, err)\n\t}\n\n\tfor _, thread := range t {\n\t\tif pid == thread.PID {\n\t\t\tthreadStates[pidStat.State]++\n\t\t\tcontinue\n\t\t}\n\t\tthreadStat, err := thread.Stat()\n\t\tif err != nil {","sourceCodeStart":138,"sourceCodeEnd":174,"githubUrl":"https://github.com/prometheus/node_exporter/blob/17ddd77c59ba27e1508e9f7894b1e55b44d6aed3/collector/processes_linux.go#L138-L174","documentation":"getThreadStates opens the task directory of a process (fs, err := procfs.NewFS / AllProcs on /proc/<pid>/task) to enumerate its threads; a non-ignored error reading the task entry is wrapped as 'error reading task for pid %d'. Missing-task errors (pid exited) are deliberately ignored and return nil.","triggerScenarios":"Reading /proc/<pid>/task for a pid fails with an error that c.isIgnoredError() does not treat as ignorable, e.g. EACCES/EPERM on the task directory during a scrape.","commonSituations":"hidepid-restricted procfs where the exporter cannot traverse another user's /proc/<pid>/task; SELinux/AppArmor denials; races where the process exited between listing and task read (these are normally silenced as ignored errors).","solutions":["Check the wrapped cause: permission errors mean the exporter user lacks access to the process's task directory — run as root or relax hidepid/LSM policy.","If an LSM (SELinux/AppArmor) denies access, add an allow rule for node_exporter to read procfs.","Update procfs/node_exporter so more transient (process-exited) errors are classified as ignorable.","Identify the pid from logs and confirm with ls -l /proc/<pid>/task as the exporter user."],"exampleFix":null,"handlingStrategy":"try-catch","validationCode":"// verify the exporter can traverse task directories\nif _, err := os.ReadDir(\"/proc/1/task\"); err != nil {\n    log.Printf(\"cannot read /proc/1/task as exporter user: %v\", err)\n}","typeGuard":null,"tryCatchPattern":"if err := c.Update(ch); err != nil {\n    if errors.Is(err, os.ErrPermission) || errors.Is(err, os.ErrNotExist) {\n        log.Printf(\"thread task read issue (permissions or pid exited): %v\", err)\n        // retry next scrape; only alert if persistent\n    }\n}","preventionTips":["Grant the exporter user read access to /proc/<pid>/task (root or hidepid gid option).","Add SELinux/AppArmor rules permitting procfs reads for node_exporter.","Keep procfs/node_exporter current so process-exit races return nil instead of errors.","Correlate errors with specific pids from the debug logs."],"tags":["linux","procfs","threads","permissions","node-exporter"],"backgroundTag":"file-read-failed","analyzedSha":"17ddd77c59ba27e1508e9f7894b1e55b44d6aed3","analyzedAt":"2026-09-07T17:54:06.211Z","contentChangedAt":"2026-09-07T17:54:06.211Z","schemaVersion":2},"datasetVersion":"2026-09-16T04:17:20.429Z"}