New thread continuing from
<https://www.postgresql.org/message-id/d4903af2-e7b7-b551-71f8-3e4a6bdc2...@2ndquadrant.com>.
Here is a extended version of Álvaro's patch that adds an errbacktrace()
function. You can do two things with this:
- Manually attach it to an ereport() call site that you want to debug.
- Set a configuration parameter like backtrace_function = 'int8in' to
debug ereport()/elog() calls in a specific function.
There was also mention of settings that would automatically produce
backtraces for PANICs etc. Those could surely be added if there is
enough interest.
For the implementation, I support both backtrace() provided by the OS as
well as using libunwind. The former seems to be supported by a number
of platforms, including glibc, macOS, and FreeBSD, so maybe we don't
need the libunwind suport. I haven't found any difference in quality in
the backtraces between the two approaches, but surely that is highly
dependent on the exact configuration.
I would welcome testing in all direction with this, to see how well it
works in different circumstances.
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
From ea79d7d04e940e70fa5b63f1be5b5272d287677c Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <pe...@eisentraut.org>
Date: Tue, 18 Jun 2019 00:36:20 +0200
Subject: [PATCH v2] Add errbacktrace() and backtrace_function GUC
---
configure | 101 ++++++++++++++++++++++++++++-
configure.in | 17 +++++
src/Makefile.global.in | 1 +
src/backend/utils/error/elog.c | 115 +++++++++++++++++++++++++++++++++
src/backend/utils/misc/guc.c | 10 +++
src/include/pg_config.h.in | 9 +++
src/include/utils/elog.h | 3 +
src/include/utils/guc.h | 1 +
8 files changed, 255 insertions(+), 2 deletions(-)
diff --git a/configure b/configure
index 8d47071e4a..a8394ecfd9 100755
--- a/configure
+++ b/configure
@@ -710,6 +710,7 @@ with_uuid
with_systemd
with_selinux
with_openssl
+with_libunwind
with_ldap
with_krb_srvnam
krb_srvtab
@@ -853,6 +854,7 @@ with_pam
with_bsd_auth
with_ldap
with_bonjour
+with_libunwind
with_openssl
with_selinux
with_systemd
@@ -1557,6 +1559,7 @@ Optional Packages:
--with-bsd-auth build with BSD Authentication support
--with-ldap build with LDAP support
--with-bonjour build with Bonjour support
+ --with-libunwind build with libunwind support
--with-openssl build with OpenSSL support
--with-selinux build with SELinux support
--with-systemd build with systemd support
@@ -7861,6 +7864,39 @@ fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $with_bonjour" >&5
$as_echo "$with_bonjour" >&6; }
+#
+# libunwind
+#
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to build with
libunwind" >&5
+$as_echo_n "checking whether to build with libunwind... " >&6; }
+
+
+
+# Check whether --with-libunwind was given.
+if test "${with_libunwind+set}" = set; then :
+ withval=$with_libunwind;
+ case $withval in
+ yes)
+
+$as_echo "#define USE_LIBUNWIND 1" >>confdefs.h
+
+ ;;
+ no)
+ :
+ ;;
+ *)
+ as_fn_error $? "no argument expected for --with-libunwind option"
"$LINENO" 5
+ ;;
+ esac
+
+else
+ with_libunwind=no
+
+fi
+
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $with_libunwind" >&5
+$as_echo "$with_libunwind" >&6; }
#
# OpenSSL
@@ -12224,6 +12260,67 @@ fi
fi
+if test "$with_libunwind" = yes; then
+ # On macOS, the library does not exist, the functionality is built
+ # into the OS.
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing
unw_getcontext" >&5
+$as_echo_n "checking for library containing unw_getcontext... " >&6; }
+if ${ac_cv_search_unw_getcontext+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ ac_func_search_save_LIBS=$LIBS
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+
+/* Override any GCC internal prototype to avoid an error.
+ Use char because int might match the return type of a GCC
+ builtin and then its argument prototype would still apply. */
+#ifdef __cplusplus
+extern "C"
+#endif
+char unw_getcontext ();
+int
+main ()
+{
+return unw_getcontext ();
+ ;
+ return 0;
+}
+_ACEOF
+for ac_lib in '' unwind; do
+ if test -z "$ac_lib"; then
+ ac_res="none required"
+ else
+ ac_res=-l$ac_lib
+ LIBS="-l$ac_lib $ac_func_search_save_LIBS"
+ fi
+ if ac_fn_c_try_link "$LINENO"; then :
+ ac_cv_search_unw_getcontext=$ac_res
+fi
+rm -f core conftest.err conftest.$ac_objext \
+ conftest$ac_exeext
+ if ${ac_cv_search_unw_getcontext+:} false; then :
+ break
+fi
+done
+if ${ac_cv_search_unw_getcontext+:} false; then :
+
+else
+ ac_cv_search_unw_getcontext=no
+fi
+rm conftest.$ac_ext
+LIBS=$ac_func_search_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_unw_getcontext"
>&5
+$as_echo "$ac_cv_search_unw_getcontext" >&6; }
+ac_res=$ac_cv_search_unw_getcontext
+if test "$ac_res" != no; then :
+ test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
+
+fi
+
+fi
+
if test "$with_libxml" = yes ; then
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for xmlSaveToBuffer in
-lxml2" >&5
$as_echo_n "checking for xmlSaveToBuffer in -lxml2... " >&6; }
@@ -12793,7 +12890,7 @@ $as_echo "#define HAVE_STDBOOL_H 1" >>confdefs.h
fi
-for ac_header in atomic.h copyfile.h crypt.h fp_class.h getopt.h ieeefp.h
ifaddrs.h langinfo.h mbarrier.h poll.h sys/epoll.h sys/ipc.h sys/prctl.h
sys/procctl.h sys/pstat.h sys/resource.h sys/select.h sys/sem.h sys/shm.h
sys/sockio.h sys/tas.h sys/un.h termios.h ucred.h utime.h wchar.h wctype.h
+for ac_header in atomic.h copyfile.h crypt.h execinfo.h fp_class.h getopt.h
ieeefp.h ifaddrs.h langinfo.h mbarrier.h poll.h sys/epoll.h sys/ipc.h
sys/prctl.h sys/procctl.h sys/pstat.h sys/resource.h sys/select.h sys/sem.h
sys/shm.h sys/sockio.h sys/tas.h sys/un.h termios.h ucred.h utime.h wchar.h
wctype.h
do :
as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header"
"$ac_includes_default"
@@ -15176,7 +15273,7 @@ fi
LIBS_including_readline="$LIBS"
LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'`
-for ac_func in cbrt clock_gettime copyfile fdatasync getifaddrs getpeerucred
getrlimit mbstowcs_l memmove poll posix_fallocate ppoll pstat
pthread_is_threaded_np readlink setproctitle setproctitle_fast setsid shm_open
strchrnul strsignal symlink sync_file_range uselocale utime utimes wcstombs_l
+for ac_func in backtrace_symbols cbrt clock_gettime copyfile fdatasync
getifaddrs getpeerucred getrlimit mbstowcs_l memmove poll posix_fallocate ppoll
pstat pthread_is_threaded_np readlink setproctitle setproctitle_fast setsid
shm_open strchrnul strsignal symlink sync_file_range uselocale utime utimes
wcstombs_l
do :
as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
diff --git a/configure.in b/configure.in
index 74938d4190..1349daf54a 100644
--- a/configure.in
+++ b/configure.in
@@ -831,6 +831,15 @@ PGAC_ARG_BOOL(with, bonjour, no,
[AC_DEFINE([USE_BONJOUR], 1, [Define to 1 to build with Bonjour
support. (--with-bonjour)])])
AC_MSG_RESULT([$with_bonjour])
+#
+# libunwind
+#
+AC_MSG_CHECKING([whether to build with libunwind])
+PGAC_ARG_BOOL(with, libunwind, no,
+ [build with libunwind support],
+ [AC_DEFINE([USE_LIBUNWIND], 1, [Define to 1 to build with
libunwind support. (--with-libunwind)])])
+AC_MSG_RESULT([$with_libunwind])
+AC_SUBST(with_libunwind)[]dnl
#
# OpenSSL
@@ -1223,6 +1232,12 @@ if test "$with_pam" = yes ; then
AC_CHECK_LIB(pam, pam_start, [], [AC_MSG_ERROR([library 'pam' is required
for PAM])])
fi
+if test "$with_libunwind" = yes; then
+ # On macOS, the library does not exist, the functionality is built
+ # into the OS.
+ AC_SEARCH_LIBS(unw_getcontext, [unwind])
+fi
+
if test "$with_libxml" = yes ; then
AC_CHECK_LIB(xml2, xmlSaveToBuffer, [], [AC_MSG_ERROR([library 'xml2'
(version >= 2.6.23) is required for XML support])])
fi
@@ -1298,6 +1313,7 @@ AC_CHECK_HEADERS(m4_normalize([
atomic.h
copyfile.h
crypt.h
+ execinfo.h
fp_class.h
getopt.h
ieeefp.h
@@ -1612,6 +1628,7 @@ LIBS_including_readline="$LIBS"
LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'`
AC_CHECK_FUNCS(m4_normalize([
+ backtrace_symbols
cbrt
clock_gettime
copyfile
diff --git a/src/Makefile.global.in b/src/Makefile.global.in
index b9d86acaa9..6e14a4b217 100644
--- a/src/Makefile.global.in
+++ b/src/Makefile.global.in
@@ -190,6 +190,7 @@ with_systemd = @with_systemd@
with_gssapi = @with_gssapi@
with_krb_srvnam = @with_krb_srvnam@
with_ldap = @with_ldap@
+with_libunwind = @with_libunwind@
with_libxml = @with_libxml@
with_libxslt = @with_libxslt@
with_llvm = @with_llvm@
diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index 8b4720ef3a..901287c335 100644
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -62,6 +62,12 @@
#ifdef HAVE_SYSLOG
#include <syslog.h>
#endif
+#ifdef HAVE_EXECINFO_H
+#include <execinfo.h>
+#endif
+#ifdef USE_LIBUNWIND
+#include <libunwind.h>
+#endif
#include "access/transam.h"
#include "access/xact.h"
@@ -166,6 +172,7 @@ static char formatted_log_time[FORMATTED_TS_LEN];
} while (0)
+static void set_backtrace(ErrorData *edata, int num_skip);
static const char *err_gettext(const char *str) pg_attribute_format_arg(1);
static void set_errdata_field(MemoryContextData *cxt, char **ptr, const char
*str);
static void write_console(const char *line, int len);
@@ -424,6 +431,12 @@ errfinish(int dummy,...)
*/
oldcontext = MemoryContextSwitchTo(ErrorContext);
+ if (!edata->backtrace &&
+ edata->funcname &&
+ backtrace_function[0] &&
+ strcmp(backtrace_function, edata->funcname) == 0)
+ set_backtrace(edata, 2);
+
/*
* Call any context callback functions. Errors occurring in callback
* functions will be treated as recursive errors --- this ensures we
will
@@ -488,6 +501,8 @@ errfinish(int dummy,...)
pfree(edata->hint);
if (edata->context)
pfree(edata->context);
+ if (edata->backtrace)
+ pfree(edata->backtrace);
if (edata->schema_name)
pfree(edata->schema_name);
if (edata->table_name)
@@ -798,6 +813,85 @@ errmsg(const char *fmt,...)
return 0; /* return value does
not matter */
}
+int
+errbacktrace(void)
+{
+ ErrorData *edata = &errordata[errordata_stack_depth];
+ MemoryContext oldcontext;
+
+ recursion_depth++;
+ CHECK_STACK_DEPTH();
+ oldcontext = MemoryContextSwitchTo(edata->assoc_context);
+
+ set_backtrace(edata, 1);
+
+ MemoryContextSwitchTo(oldcontext);
+ recursion_depth--;
+
+ return 0;
+}
+
+static void
+set_backtrace(ErrorData *edata, int num_skip)
+{
+ StringInfoData errtrace;
+
+ initStringInfo(&errtrace);
+
+#ifdef USE_LIBUNWIND
+ {
+ unw_context_t context;
+ unw_cursor_t cursor;
+ int n = 0;
+
+ unw_getcontext(&context);
+ unw_init_local(&cursor, &context);
+
+ while (unw_step(&cursor))
+ {
+ unw_word_t ip, off;
+ char symbol[256] = "<unknown>";
+
+ if (n < num_skip - 1)
+ {
+ n++;
+ continue;
+ }
+
+ unw_get_reg(&cursor, UNW_REG_IP, &ip);
+ unw_get_proc_name(&cursor, symbol, sizeof(symbol),
&off);
+
+ appendStringInfo(&errtrace,
+ "#%-2d %s+0x%llx
[0x%016llx]\n",
+ n - 1,
+ symbol,
+ (unsigned long long)
off,
+ (unsigned long long)
ip);
+
+ n++;
+ }
+ }
+#elif defined(HAVE_EXECINFO_H) && defined(HAVE_BACKTRACE_SYMBOLS)
+ {
+ void *buf[100];
+ int nframes;
+ char **strfrms;
+
+ nframes = backtrace(buf, sizeof(buf));
+ strfrms = backtrace_symbols(buf, nframes);
+ if (strfrms == NULL)
+ return;
+
+ for (int i = num_skip; i < nframes; i++)
+ appendStringInfo(&errtrace, "%s\n", strfrms[i]);
+ free(strfrms);
+ }
+#else
+ appendStringInfoString(&errtrace, "backtrace not supported");
+#endif
+
+ edata->backtrace = errtrace.data;
+}
/*
* errmsg_internal --- add a primary error message text to the current error
@@ -1353,6 +1447,12 @@ elog_finish(int elevel, const char *fmt,...)
recursion_depth++;
oldcontext = MemoryContextSwitchTo(edata->assoc_context);
+ if (!edata->backtrace &&
+ edata->funcname &&
+ backtrace_function[0] &&
+ strcmp(backtrace_function, edata->funcname) == 0)
+ set_backtrace(edata, 2);
+
edata->message_id = fmt;
EVALUATE_MESSAGE(edata->domain, message, false, false);
@@ -1509,6 +1609,8 @@ CopyErrorData(void)
newedata->hint = pstrdup(newedata->hint);
if (newedata->context)
newedata->context = pstrdup(newedata->context);
+ if (newedata->backtrace)
+ newedata->backtrace = pstrdup(newedata->backtrace);
if (newedata->schema_name)
newedata->schema_name = pstrdup(newedata->schema_name);
if (newedata->table_name)
@@ -1547,6 +1649,8 @@ FreeErrorData(ErrorData *edata)
pfree(edata->hint);
if (edata->context)
pfree(edata->context);
+ if (edata->backtrace)
+ pfree(edata->backtrace);
if (edata->schema_name)
pfree(edata->schema_name);
if (edata->table_name)
@@ -1622,6 +1726,8 @@ ThrowErrorData(ErrorData *edata)
newedata->hint = pstrdup(edata->hint);
if (edata->context)
newedata->context = pstrdup(edata->context);
+ if (edata->backtrace)
+ newedata->backtrace = pstrdup(edata->backtrace);
/* assume message_id is not available */
if (edata->schema_name)
newedata->schema_name = pstrdup(edata->schema_name);
@@ -1689,6 +1795,8 @@ ReThrowError(ErrorData *edata)
newedata->hint = pstrdup(newedata->hint);
if (newedata->context)
newedata->context = pstrdup(newedata->context);
+ if (newedata->backtrace)
+ newedata->backtrace = pstrdup(newedata->backtrace);
if (newedata->schema_name)
newedata->schema_name = pstrdup(newedata->schema_name);
if (newedata->table_name)
@@ -2914,6 +3022,13 @@ send_message_to_server_log(ErrorData *edata)
append_with_tabs(&buf, edata->context);
appendStringInfoChar(&buf, '\n');
}
+ if (edata->backtrace)
+ {
+ log_line_prefix(&buf, edata);
+ appendStringInfoString(&buf, _("BACKTRACE: "));
+ append_with_tabs(&buf, edata->backtrace);
+ appendStringInfoChar(&buf, '\n');
+ }
if (Log_error_verbosity >= PGERROR_VERBOSE)
{
/* assume no newlines in funcname or filename... */
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 1208eb9a68..328e5b6699 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -514,6 +514,7 @@ int log_temp_files = -1;
double log_statement_sample_rate = 1.0;
double log_xact_sample_rate = 0;
int trace_recovery_messages = LOG;
+char *backtrace_function;
int temp_file_limit = -1;
@@ -4213,6 +4214,15 @@ static struct config_string ConfigureNamesString[] =
NULL, NULL, NULL
},
+ {
+ {"backtrace_function", PGC_SUSET, DEVELOPER_OPTIONS,
+ gettext_noop("Log backtrace for errors in this
function."),
+ },
+ &backtrace_function,
+ "",
+ NULL, NULL, NULL
+ },
+
/* End-of-list marker */
{
{NULL, 0, 0, NULL, NULL}, NULL, NULL, NULL, NULL, NULL
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 6cd4cfed0a..6959ce6c61 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -96,6 +96,9 @@
/* Define to 1 if you have the <atomic.h> header file. */
#undef HAVE_ATOMIC_H
+/* Define to 1 if you have the `backtrace_symbols' function. */
+#undef HAVE_BACKTRACE_SYMBOLS
+
/* Define to 1 if you have the `BIO_get_data' function. */
#undef HAVE_BIO_GET_DATA
@@ -201,6 +204,9 @@
/* Define to 1 if you have the <editline/readline.h> header file. */
#undef HAVE_EDITLINE_READLINE_H
+/* Define to 1 if you have the <execinfo.h> header file. */
+#undef HAVE_EXECINFO_H
+
/* Define to 1 if you have the `fdatasync' function. */
#undef HAVE_FDATASYNC
@@ -922,6 +928,9 @@
/* Define to 1 to build with LDAP support. (--with-ldap) */
#undef USE_LDAP
+/* Define to 1 to build with libunwind support. (--with-libunwind) */
+#undef USE_LIBUNWIND
+
/* Define to 1 to build with XML support. (--with-libxml) */
#undef USE_LIBXML
diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h
index dbfd8efd26..b58aee792a 100644
--- a/src/include/utils/elog.h
+++ b/src/include/utils/elog.h
@@ -189,6 +189,8 @@ extern int errcontext_msg(const char *fmt,...)
pg_attribute_printf(1, 2);
extern int errhidestmt(bool hide_stmt);
extern int errhidecontext(bool hide_ctx);
+extern int errbacktrace(void);
+
extern int errfunction(const char *funcname);
extern int errposition(int cursorpos);
@@ -362,6 +364,7 @@ typedef struct ErrorData
char *detail_log; /* detail error message for server log
only */
char *hint; /* hint message */
char *context; /* context message */
+ char *backtrace; /* backtrace */
const char *message_id; /* primary message's id (original
string) */
char *schema_name; /* name of schema */
char *table_name; /* name of table */
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index e709177c37..032f4f16ab 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -255,6 +255,7 @@ extern int log_min_duration_statement;
extern int log_temp_files;
extern double log_statement_sample_rate;
extern double log_xact_sample_rate;
+extern char *backtrace_function;
extern int temp_file_limit;
--
2.22.0
