[jira] [Created] (DISPATCH-1373) the log system mutex is held far too long

["Ken Giusti (JIRA)" <ji...@apache.org>]

Ken Giusti created DISPATCH-1373:
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             Summary: the log system mutex is held far too long
                 Key: DISPATCH-1373
                 URL: https://issues.apache.org/jira/browse/DISPATCH-1373
             Project: Qpid Dispatch
          Issue Type: Bug
          Components: Router Node
    Affects Versions: 1.8.0
            Reporter: Ken Giusti
             Fix For: 1.9.0


The log code holds the log mutex(s) too long.  Depending on the log level (trace+ is worst) the lock has been observed being held for > 30 milliseconds.

The log lock is a singleton that is acquired by all calls to qd_log (active log level only) - which means it is a global lock.

It appears as if the lock is held while doing I/O and alloc/dealloc'ing memory - which may be expensive (in qd_vlog_impl() in log.c):

 

{{    // Bounded buffer of log entries, keep most recent.}}
{{    *sys_mutex_lock(log_lock);*}}
{{    qd_log_entry_t *entry = new_qd_log_entry_t();}}
{{    DEQ_ITEM_INIT(entry);}}
{{    entry->module = source->module;}}
{{    entry->level  = level;}}
{{    entry->file   = file ? strdup(file) : 0;}}
{{    entry->line   = line;}}
{{    gettimeofday(&entry->time, NULL);}}
{{    vsnprintf(entry->text, TEXT_MAX, fmt, ap);}}
{{    write_log(source, entry);}}
{{    DEQ_INSERT_TAIL(entries, entry);}}
{{    if (DEQ_SIZE(entries) > LIST_MAX)}}
{{        qd_log_entry_free_lh(DEQ_HEAD(entries));}}
{{    *sys_mutex_unlock(log_lock);*}}{{}}

 



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