Show PIDs of lock holders and waiters in log_lock_waits log message.

Christian Kruse, reviewed by Kumar Rajeev Rastogi.

diff --git a/doc/src/sgml/sources.sgml b/doc/src/sgml/sources.sgml
index 881b0c31a75a92029d5c91d3c2af52d83a154226..aa2080742d48329d277e9766f88f9d4348b7980d 100644 (file)
--- a/doc/src/sgml/sources.sgml
+++ b/doc/src/sgml/sources.sgml
@@ -249,6 +249,15 @@ ereport(ERROR,
      sent to the client.
     </para>
    </listitem>
+   <listitem>
+    <para>
+     <function>errdetail_log_plural(const char *fmt_singuar, const char
+     *fmt_plural, unsigned long n, ...)</function> is like
+     <function>errdetail_log</>, but with support for various plural forms of
+     the message.
+     For more information see <xref linkend="nls-guidelines">.
+    </para>
+   </listitem>
    <listitem>
     <para>
      <function>errhint(const char *msg, ...)</function> supplies an optional

diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index f595a0747c1f775ae021bf2bf6d2a4f65ae236fb..5cd8fcec45064b1c0c7ed99471c086ca8716f174 100644 (file)
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -1208,13 +1208,23 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
         */
        if (log_lock_waits && deadlock_state != DS_NOT_YET_CHECKED)
        {
-           StringInfoData buf;
+           StringInfoData buf,
+                       lock_waiters_sbuf,
+                       lock_holders_sbuf;
            const char *modename;
            long        secs;
            int         usecs;
            long        msecs;
+           SHM_QUEUE  *procLocks;
+           PROCLOCK   *proclock;
+           bool        first_holder = true,
+                       first_waiter = true;
+           int         lockHoldersNum = 0;
 
            initStringInfo(&buf);
+           initStringInfo(&lock_waiters_sbuf);
+           initStringInfo(&lock_holders_sbuf);
+
            DescribeLockTag(&buf, &locallock->tag.lock);
            modename = GetLockmodeName(locallock->tag.lock.locktag_lockmethodid,
                                       lockmode);
@@ -1224,10 +1234,67 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
            msecs = secs * 1000 + usecs / 1000;
            usecs = usecs % 1000;
 
+           /*
+            * we loop over the lock's procLocks to gather a list of all
+            * holders and waiters. Thus we will be able to provide more
+            * detailed information for lock debugging purposes.
+            *
+            * lock->procLocks contains all processes which hold or wait for
+            * this lock.
+            */
+
+           LWLockAcquire(partitionLock, LW_SHARED);
+
+           procLocks = &(lock->procLocks);
+           proclock = (PROCLOCK *) SHMQueueNext(procLocks, procLocks,
+                                              offsetof(PROCLOCK, lockLink));
+
+           while (proclock)
+           {
+               /*
+                * we are a waiter if myProc->waitProcLock == proclock; we are
+                * a holder if it is NULL or something different
+                */
+               if (proclock->tag.myProc->waitProcLock == proclock)
+               {
+                   if (first_waiter)
+                   {
+                       appendStringInfo(&lock_waiters_sbuf, "%d",
+                                        proclock->tag.myProc->pid);
+                       first_waiter = false;
+                   }
+                   else
+                       appendStringInfo(&lock_waiters_sbuf, ", %d",
+                                        proclock->tag.myProc->pid);
+               }
+               else
+               {
+                   if (first_holder)
+                   {
+                       appendStringInfo(&lock_holders_sbuf, "%d",
+                                        proclock->tag.myProc->pid);
+                       first_holder = false;
+                   }
+                   else
+                       appendStringInfo(&lock_holders_sbuf, ", %d",
+                                        proclock->tag.myProc->pid);
+
+                   lockHoldersNum++;
+               }
+
+               proclock = (PROCLOCK *) SHMQueueNext(procLocks, &proclock->lockLink,
+                                              offsetof(PROCLOCK, lockLink));
+           }
+
+           LWLockRelease(partitionLock);
+
            if (deadlock_state == DS_SOFT_DEADLOCK)
                ereport(LOG,
                        (errmsg("process %d avoided deadlock for %s on %s by rearranging queue order after %ld.%03d ms",
-                             MyProcPid, modename, buf.data, msecs, usecs)));
+                               MyProcPid, modename, buf.data, msecs, usecs),
+                        (errdetail_log_plural("Process holding the lock: %s. Wait queue: %s.",
+                          "Processes holding the lock: %s. Wait queue: %s.",
+                                              lockHoldersNum, lock_holders_sbuf.data, lock_waiters_sbuf.data))));
            else if (deadlock_state == DS_HARD_DEADLOCK)
            {
                /*
@@ -1239,13 +1306,19 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
                 */
                ereport(LOG,
                        (errmsg("process %d detected deadlock while waiting for %s on %s after %ld.%03d ms",
-                             MyProcPid, modename, buf.data, msecs, usecs)));
+                               MyProcPid, modename, buf.data, msecs, usecs),
+                        (errdetail_log_plural("Process holding the lock: %s. Wait queue: %s.",
+                          "Processes holding the lock: %s. Wait queue: %s.",
+                                              lockHoldersNum, lock_holders_sbuf.data, lock_waiters_sbuf.data))));
            }
 
            if (myWaitStatus == STATUS_WAITING)
                ereport(LOG,
                        (errmsg("process %d still waiting for %s on %s after %ld.%03d ms",
-                             MyProcPid, modename, buf.data, msecs, usecs)));
+                               MyProcPid, modename, buf.data, msecs, usecs),
+                        (errdetail_log_plural("Process holding the lock: %s. Wait queue: %s.",
+                          "Processes holding the lock: %s. Wait queue: %s.",
+                                              lockHoldersNum, lock_holders_sbuf.data, lock_waiters_sbuf.data))));
            else if (myWaitStatus == STATUS_OK)
                ereport(LOG,
                    (errmsg("process %d acquired %s on %s after %ld.%03d ms",
@@ -1265,7 +1338,10 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
                if (deadlock_state != DS_HARD_DEADLOCK)
                    ereport(LOG,
                            (errmsg("process %d failed to acquire %s on %s after %ld.%03d ms",
-                             MyProcPid, modename, buf.data, msecs, usecs)));
+                               MyProcPid, modename, buf.data, msecs, usecs),
+                            (errdetail_log_plural("Process holding the lock: %s. Wait queue: %s.",
+                          "Processes holding the lock: %s. Wait queue: %s.",
+                                                  lockHoldersNum, lock_holders_sbuf.data, lock_waiters_sbuf.data))));
            }
 
            /*
@@ -1275,6 +1351,8 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
            deadlock_state = DS_NO_DEADLOCK;
 
            pfree(buf.data);
+           pfree(lock_holders_sbuf.data);
+           pfree(lock_waiters_sbuf.data);
        }
    } while (myWaitStatus == STATUS_WAITING);
 

diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index 8705586d5659415ce9ce7df3f656f2f222ada292..d28b74941152673d9d24c51af267fe788c121e6a 100644 (file)
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -937,6 +937,28 @@ errdetail_log(const char *fmt,...)
    return 0;                   /* return value does not matter */
 }
 
+/*
+ * errdetail_log_plural --- add a detail_log error message text to the current error
+ * with support for pluralization of the message text
+ */
+int
+errdetail_log_plural(const char *fmt_singular, const char *fmt_plural,
+                    unsigned long n,...)
+{
+   ErrorData  *edata = &errordata[errordata_stack_depth];
+   MemoryContext oldcontext;
+
+   recursion_depth++;
+   CHECK_STACK_DEPTH();
+   oldcontext = MemoryContextSwitchTo(edata->assoc_context);
+
+   EVALUATE_MESSAGE_PLURAL(edata->domain, detail_log, false);
+
+   MemoryContextSwitchTo(oldcontext);
+   recursion_depth--;
+   return 0;                   /* return value does not matter */
+}
+
 
 /*
  * errdetail_plural --- add a detail error message text to the current error,

diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h
index d7916c22f97154c206a161b25dc4e0fc149e1174..427d52d878cec4003975abcad7b1a93bea549c7d 100644 (file)
--- a/src/include/utils/elog.h
+++ b/src/include/utils/elog.h
@@ -181,6 +181,14 @@ errdetail_log(const char *fmt,...)
    the supplied arguments. */
 __attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 2)));
 
+extern int
+errdetail_log_plural(const char *fmt_singular, const char *fmt_plural,
+                    unsigned long n,...)
+/* This extension allows gcc to check the format string for consistency with
+   the supplied arguments. */
+__attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 4)))
+__attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 4)));
+
 extern int
 errdetail_plural(const char *fmt_singular, const char *fmt_plural,
                 unsigned long n,...)