diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 44956c15b5aae8785814751e4b6e7e114d5a5f1f..ba64f2395c08bbb227eb58899e0d8d67a423667d 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -58,6 +58,7 @@
#include "storage/pg_shmem.h"
#include "storage/pmsignal.h"
#include "storage/procsignal.h"
+#include "utils/ascii.h"
#include "utils/guc.h"
#include "utils/memutils.h"
#include "utils/ps_status.h"
@@ -2228,6 +2229,7 @@ static PgBackendStatus *MyBEEntry = NULL;
static char *BackendClientHostnameBuffer = NULL;
static char *BackendAppnameBuffer = NULL;
static char *BackendActivityBuffer = NULL;
+static Size BackendActivityBufferSize = 0;
/*
@@ -2310,9 +2312,12 @@ CreateSharedBackendStatus(void)
}
/* Create or attach to the shared activity buffer */
- size = mul_size(pgstat_track_activity_query_size, MaxBackends);
+ BackendActivityBufferSize = mul_size(pgstat_track_activity_query_size,
+ MaxBackends);
BackendActivityBuffer = (char *)
- ShmemInitStruct("Backend Activity Buffer", size, &found);
+ ShmemInitStruct("Backend Activity Buffer",
+ BackendActivityBufferSize,
+ &found);
if (!found)
{
@@ -2751,6 +2756,70 @@ pgstat_get_backend_current_activity(int pid, bool checkUser)
return "<backend information not available>";
}
+/* ----------
+ * pgstat_get_crashed_backend_activity() -
+ *
+ * Return a string representing the current activity of the backend with
+ * the specified PID. Like the function above, but reads shared memory with
+ * the expectation that it may be corrupt. Returns either a pointer to a
+ * constant string, or writes into the 'buffer' argument and returns it.
+ *
+ * This function is only intended to be used by postmaster to report the
+ * query that crashed the backend. In particular, no attempt is made to
+ * follow the correct concurrency protocol when accessing the
+ * BackendStatusArray. But that's OK, in the worst case we'll return a
+ * corrupted message. We also must take care not to trip on ereport(ERROR).
+ *
+ * Note: return strings for special cases match pg_stat_get_backend_activity.
+ * ----------
+ */
+const char *
+pgstat_get_crashed_backend_activity(int pid, char *buffer,
+ int len)
+{
+ volatile PgBackendStatus *beentry;
+ int i;
+
+ beentry = BackendStatusArray;
+ for (i = 1; i <= MaxBackends; i++)
+ {
+ if (beentry->st_procpid == pid)
+ {
+ /* Read pointer just once, so it can't change after validation */
+ const char *activity = beentry->st_activity;
+ const char *activity_last;
+
+ /*
+ * We can't access activity pointer before we verify that it
+ * falls into BackendActivityBuffer. To make sure that the entire
+ * string including its ending is contained within the buffer,
+ * we subtract one activity length from it.
+ */
+ activity_last = BackendActivityBuffer + BackendActivityBufferSize
+ - pgstat_track_activity_query_size;
+
+ if (activity < BackendActivityBuffer ||
+ activity > activity_last)
+ return "<command string corrupt>";
+
+ if (*(activity) == '\0')
+ return "<command string empty>";
+
+ /*
+ * Copy only ASCII-safe characters so we don't run into encoding
+ * problems when reporting the message.
+ */
+ ascii_safe_strncpy(buffer, activity, len);
+
+ return buffer;
+ }
+
+ beentry++;
+ }
+
+ /* PID not found */
+ return "<backend information not available>";
+}
/* ------------------------------------------------------------
* Local support functions follow
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index dd7493cf9dd997543b225c2f2eb886c751dd7ab0..5476975f765484717aa5474da538e14aa0517972 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -2777,6 +2777,13 @@ HandleChildCrash(int pid, int exitstatus, const char *procname)
static void
LogChildExit(int lev, const char *procname, int pid, int exitstatus)
{
+ char activity_buffer[1024]; /* default track_activity_query_size */
+ const char *activity;
+
+ activity = pgstat_get_crashed_backend_activity(pid,
+ activity_buffer,
+ sizeof(activity_buffer));
+
if (WIFEXITED(exitstatus))
ereport(lev,
@@ -2784,7 +2791,8 @@ LogChildExit(int lev, const char *procname, int pid, int exitstatus)
translator: %s is a noun phrase describing a child process, such as
"server process" */
(errmsg("%s (PID %d) exited with exit code %d",
- procname, pid, WEXITSTATUS(exitstatus))));
+ procname, pid, WEXITSTATUS(exitstatus)),
+ errdetail("Running query: %s", activity)));
else if (WIFSIGNALED(exitstatus))
#if defined(WIN32)
ereport(lev,
@@ -2794,7 +2802,8 @@ LogChildExit(int lev, const char *procname, int pid, int exitstatus)
"server process" */
(errmsg("%s (PID %d) was terminated by exception 0x%X",
procname, pid, WTERMSIG(exitstatus)),
- errhint("See C include file \"ntstatus.h\" for a description of the hexadecimal value.")));
+ errhint("See C include file \"ntstatus.h\" for a description of the hexadecimal value."),
+ errdetail("Running query: %s", activity)));
#elif defined(HAVE_DECL_SYS_SIGLIST) && HAVE_DECL_SYS_SIGLIST
ereport(lev,
@@ -2804,7 +2813,8 @@ LogChildExit(int lev, const char *procname, int pid, int exitstatus)
(errmsg("%s (PID %d) was terminated by signal %d: %s",
procname, pid, WTERMSIG(exitstatus),
WTERMSIG(exitstatus) < NSIG ?
- sys_siglist[WTERMSIG(exitstatus)] : "(unknown)")));
+ sys_siglist[WTERMSIG(exitstatus)] : "(unknown)"),
+ errdetail("Running query: %s", activity)));
#else
ereport(lev,
@@ -2812,7 +2822,8 @@ LogChildExit(int lev, const char *procname, int pid, int exitstatus)
translator: %s is a noun phrase describing a child process, such as
"server process" */
(errmsg("%s (PID %d) was terminated by signal %d",
- procname, pid, WTERMSIG(exitstatus))));
+ procname, pid, WTERMSIG(exitstatus)),
+ errdetail("Running query: %s", activity)));
#endif
else
ereport(lev,
@@ -2821,7 +2832,8 @@ LogChildExit(int lev, const char *procname, int pid, int exitstatus)
translator: %s is a noun phrase describing a child process, such as
"server process" */
(errmsg("%s (PID %d) exited with unrecognized status %d",
- procname, pid, exitstatus)));
+ procname, pid, exitstatus),
+ errdetail("Running query: %s", activity)));
}
/*
diff --git a/src/backend/utils/adt/ascii.c b/src/backend/utils/adt/ascii.c
index 7ecf4949b5f070c2568e066aab0622eb67c24bc4..7c9e96a04f60cd9819957762d9b326082730e254 100644
--- a/src/backend/utils/adt/ascii.c
+++ b/src/backend/utils/adt/ascii.c
@@ -158,3 +158,37 @@ to_ascii_default(PG_FUNCTION_ARGS)
PG_RETURN_TEXT_P(encode_to_ascii(data, enc));
}
+
+/* ----------
+ * "Escape" a string in unknown encoding to a valid ASCII string.
+ * Replace non-ASCII bytes with '?'
+ * This must not trigger ereport(ERROR), as it is called from postmaster.
+ *
+ * Unlike C strncpy(), the result is always terminated with exactly one null
+ * byte.
+ * ----------
+ */
+void
+ascii_safe_strncpy(char *dest, const char *src, int len)
+{
+ int i;
+
+ for (i = 0; i < (len - 1); i++)
+ {
+ unsigned char ch = src[i]; /* use unsigned char here to avoid compiler warning */
+
+ if (ch == '\0')
+ break;
+ /* Keep printable ASCII characters */
+ if (32 <= ch && ch <= 127)
+ dest[i] = ch;
+ /* White-space is also OK */
+ else if (ch == '\n' || ch == '\r' || ch == '\t')
+ dest[i] = ch;
+ /* Everything else is replaced with '?' */
+ else
+ dest[i] = '?';
+ }
+
+ dest[i] = '\0';
+}
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 20c4d4354e920fd6e761b49a2f696737b1caa3ae..d0f1927efb21218ab60e64667f2e4cfca43bcac3 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -720,6 +720,8 @@ extern void pgstat_report_appname(const char *appname);
extern void pgstat_report_xact_timestamp(TimestampTz tstamp);
extern void pgstat_report_waiting(bool waiting);
extern const char *pgstat_get_backend_current_activity(int pid, bool checkUser);
+extern const char *pgstat_get_crashed_backend_activity(int pid, char *buffer,
+ int len);
extern PgStat_TableStatus *find_tabstat_entry(Oid rel_id);
extern PgStat_BackendFunctionEntry *find_funcstat_entry(Oid func_id);
diff --git a/src/include/utils/ascii.h b/src/include/utils/ascii.h
index ad70e037bd7eae328ce1d446d39c9ebab0b5efe5..adeddb5626fa9469b9ce091426e18e9003d04118 100644
--- a/src/include/utils/ascii.h
+++ b/src/include/utils/ascii.h
@@ -16,5 +16,6 @@
extern Datum to_ascii_encname(PG_FUNCTION_ARGS);
extern Datum to_ascii_enc(PG_FUNCTION_ARGS);
extern Datum to_ascii_default(PG_FUNCTION_ARGS);
+extern void ascii_safe_strncpy(char *dest, const char *src, int len);
#endif /* _ASCII_H_ */