Add some checkpoint/restartpoint status to ps display

This is done for end-of-recovery and shutdown checkpoints/restartpoints
(end-of-recovery restartpoints don't exist) rather than all types of
checkpoints, in cases where it may not be possible to rely on
pg_stat_activity to get a status from the startup or checkpointer
processes.

For example, at the end of a crash recovery, this is useful to know if a
checkpoint is running in the startup process, while previously the ps
display may only show some information about "recovering" something,
that can be confusing while a checkpoint runs.

Author: Justin Pryzby
Reviewed-by: Nathan Bossart, Kirk Jamison, Fujii Masao, Michael Paquier
Discussion: https://postgr.es/m/20200818225238[email protected]

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 7e81ce4f173f9b2968b7df964531d7802e0e8b89..8dd225c2e140ac13273be1337935faf749e0322b 100644 (file)
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -8687,6 +8687,39 @@ UpdateCheckPointDistanceEstimate(uint64 nbytes)
            (0.90 * CheckPointDistanceEstimate + 0.10 * (double) nbytes);
 }
 
+/*
+ * Update the ps display for a process running a checkpoint.  Note that
+ * this routine should not do any allocations so as it can be called
+ * from a critical section.
+ */
+static void
+update_checkpoint_display(int flags, bool restartpoint, bool reset)
+{
+   /*
+    * The status is reported only for end-of-recovery and shutdown
+    * checkpoints or shutdown restartpoints.  Updating the ps display is
+    * useful in those situations as it may not be possible to rely on
+    * pg_stat_activity to see the status of the checkpointer or the startup
+    * process.
+    */
+   if ((flags & (CHECKPOINT_END_OF_RECOVERY | CHECKPOINT_IS_SHUTDOWN)) == 0)
+       return;
+
+   if (reset)
+       set_ps_display("");
+   else
+   {
+       char        activitymsg[128];
+
+       snprintf(activitymsg, sizeof(activitymsg), "performing %s%s%s",
+                (flags & CHECKPOINT_END_OF_RECOVERY) ? "end-of-recovery " : "",
+                (flags & CHECKPOINT_IS_SHUTDOWN) ? "shutdown " : "",
+                restartpoint ? "restartpoint" : "checkpoint");
+       set_ps_display(activitymsg);
+   }
+}
+
+
 /*
  * Perform a checkpoint --- either during shutdown, or on-the-fly
  *
@@ -8905,6 +8938,9 @@ CreateCheckPoint(int flags)
    if (log_checkpoints)
        LogCheckpointStart(flags, false);
 
+   /* Update the process title */
+   update_checkpoint_display(flags, false, false);
+
    TRACE_POSTGRESQL_CHECKPOINT_START(flags);
 
    /*
@@ -9120,6 +9156,9 @@ CreateCheckPoint(int flags)
    /* Real work is done, but log and update stats before releasing lock. */
    LogCheckpointEnd(false);
 
+   /* Reset the process title */
+   update_checkpoint_display(flags, false, true);
+
    TRACE_POSTGRESQL_CHECKPOINT_DONE(CheckpointStats.ckpt_bufs_written,
                                     NBuffers,
                                     CheckpointStats.ckpt_segs_added,
@@ -9374,6 +9413,9 @@ CreateRestartPoint(int flags)
    if (log_checkpoints)
        LogCheckpointStart(flags, true);
 
+   /* Update the process title */
+   update_checkpoint_display(flags, true, false);
+
    CheckPointGuts(lastCheckPoint.redo, flags);
 
    /*
@@ -9492,6 +9534,9 @@ CreateRestartPoint(int flags)
    /* Real work is done, but log and update before releasing lock. */
    LogCheckpointEnd(true);
 
+   /* Reset the process title */
+   update_checkpoint_display(flags, true, true);
+
    xtime = GetLatestXTime();
    ereport((log_checkpoints ? LOG : DEBUG2),
            (errmsg("recovery restart point at %X/%X",