[master] give threads unique names to assist debugging

4602.	[func]		Threads are now set to human-readable
			names to assist debugging, when supported by
			the OS. [RT #43234]

CHANGES

@@ -1,3 +1,7 @@
+4602.	[func]		Threads are now set to human-readable
+			names to assist debugging, when supported by
+			the OS. [RT #43234]
+
 4601.	[bug]		Reject incorrect RSA key lengths during key
 			generation and and sign/verify context
 			creation. [RT #45043]

config.h.in

@@ -383,6 +383,15 @@ int sigwait(const unsigned int *set, int *sig);
 /* Support for PTHREAD_MUTEX_ADAPTIVE_NP */
 #undef HAVE_PTHREAD_MUTEX_ADAPTIVE_NP
 
+/* Define to 1 if you have the <pthread_np.h> header file. */
+#undef HAVE_PTHREAD_NP_H
+
+/* Define to 1 if you have the `pthread_setname_np' function. */
+#undef HAVE_PTHREAD_SETNAME_NP
+
+/* Define to 1 if you have the `pthread_set_name_np' function. */
+#undef HAVE_PTHREAD_SET_NAME_NP
+
 /* Define to 1 if you have the `pthread_yield' function. */
 #undef HAVE_PTHREAD_YIELD
 

configure

@@ -15665,6 +15665,32 @@ fi
 			;;
 	esac
 
+	# Look for functions relating to thread naming
+	for ac_func in pthread_setname_np pthread_set_name_np
+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"
+if eval test \"x\$"$as_ac_var"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_func" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+done
+
+	for ac_header in pthread_np.h
+do :
+  ac_fn_c_check_header_mongrel "$LINENO" "pthread_np.h" "ac_cv_header_pthread_np_h" "$ac_includes_default"
+if test "x$ac_cv_header_pthread_np_h" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_PTHREAD_NP_H 1
+_ACEOF
+
+fi
+
+done
+
+
 	#
 	# Look for sysconf to allow detection of the number of processors.
 	#

configure.in

@@ -1351,6 +1351,10 @@ then
 			;;
 	esac
 
+	# Look for functions relating to thread naming
+	AC_CHECK_FUNCS(pthread_setname_np pthread_set_name_np)
+	AC_CHECK_HEADERS(pthread_np.h)
+
 	#
 	# Look for sysconf to allow detection of the number of processors.
 	#

doc/arm/notes.xml

@@ -266,6 +266,16 @@
 
   <section xml:id="relnotes_changes"><info><title>Feature Changes</title></info>
     <itemizedlist>
+      <listitem>
+	<para>
+	  Threads in <command>named</command> are now set to human-readable
+	  names to assist debugging on operating systems that support that.
+	  Threads will have names such as "isc-timer", "isc-sockmgr",
+	  "isc-worker0001", and so on. This will affect the reporting of
+	  subsidiary thread names in <command>ps</command> and
+	  <command>top</command>, but not the main thread. [RT #43234]
+	</para>
+      </listitem>
       <listitem>
 	<para>
 	  The Response Policy Zone (RPZ) implementation has been
@@ -313,55 +323,7 @@
     <itemizedlist>
       <listitem>
 	<para>
-	  A synthesized CNAME record appearing in a response before the
+	  None.
-	  associated DNAME could be cached, when it should not have been.
-	  This was a regression introduced while addressing CVE-2016-8864.
-	  [RT #44318]
-	</para>
-      </listitem>
-      <listitem>
-	<para>
-	  <command>named</command> could deadlock if multiple changes
-	  to NSEC/NSEC3 parameters for the same zone were being processed
-	  at the same time. [RT #42770]
-	</para>
-      </listitem>
-      <listitem>
-	<para>
-	  <command>named</command> could trigger an assertion when
-	  sending NOTIFY messages. [RT #44019]
-	</para>
-      </listitem>
-      <listitem>
-	<para>
-	  Referencing a nonexistent zone in a <command>response-policy</command>
-	  statement could cause an assertion failure during configuration.
-	  [RT #43787]
-	</para>
-      </listitem>
-      <listitem>
-	<para>
-	  <command>rndc addzone</command> could cause a crash
-	  when attempting to add a zone with a type other than
-	  <command>master</command> or <command>slave</command>.
-	  Such zones are now rejected. [RT #43665]
-	</para>
-      </listitem>
-      <listitem>
-	<para>
-	  <command>named</command> could hang when encountering log
-	  file names with large apparent gaps in version number (for
-	  example, when files exist called "logfile.0", "logfile.1",
-	  and "logfile.1482954169").  This is now handled correctly.
-	  [RT #38688]
-	</para>
-      </listitem>
-      <listitem>
-	<para>
-	  If a zone was updated while <command>named</command> was
-	  processing a query for nonexistent data, it could return
-	  out-of-sync NSEC3 records causing potential DNSSEC validation
-	  failure. [RT #43247]
 	</para>
       </listitem>
     </itemizedlist>

lib/isc/nothreads/include/isc/thread.h

@@ -19,6 +19,9 @@ ISC_LANG_BEGINDECLS
 void
 isc_thread_setconcurrency(unsigned int level);
 
+void
+isc_thread_setname(isc_thread_t, const char *);
+
 #define isc_thread_self() ((unsigned long)0)
 #define isc_thread_yield() ((void)0)
 

lib/isc/nothreads/thread.c

@@ -17,3 +17,8 @@ void
 isc_thread_setconcurrency(unsigned int level) {
 	UNUSED(level);
 }
+
+void isc_thread_setname(isc_thread_t thread, const char *name) {
+	UNUSED(thread);
+	UNUSED(name);
+}

lib/isc/pthreads/include/isc/thread.h

@@ -15,6 +15,10 @@
 
 #include <pthread.h>
 
+#if defined(HAVE_PTHREAD_NP_H)
+#include <pthread_np.h>
+#endif
+
 #include <isc/lang.h>
 #include <isc/result.h>
 
@@ -35,6 +39,9 @@ isc_thread_setconcurrency(unsigned int level);
 void
 isc_thread_yield(void);
 
+void
+isc_thread_setname(isc_thread_t, const char *);
+
 /* XXX We could do fancier error handling... */
 
 #define isc_thread_join(t, rp) \

lib/isc/pthreads/thread.c

@@ -70,6 +70,22 @@ isc_thread_setconcurrency(unsigned int level) {
 #endif
 }
 
+void
+isc_thread_setname(isc_thread_t thread, const char *name) {
+#if defined(HAVE_PTHREAD_SETNAME_NP) && defined(_GNU_SOURCE)
+	/*
+	 * macOS has pthread_setname_np but only works on the
+	 * current thread so it's not used here
+	*/
+	(void)pthread_setname_np(thread, name);
+#elif defined(HAVE_PTHREAD_SET_NAME_NP)
+	(void)pthread_set_name_np(thread, name);
+#else
+	UNUSED(thread);
+	UNUSED(name);
+#endif
+}
+
 void
 isc_thread_yield(void) {
 #if defined(HAVE_SCHED_YIELD)

lib/isc/task.c

@@ -1449,6 +1449,10 @@ isc__taskmgr_create(isc_mem_t *mctx, unsigned int workers,
 		if (isc_thread_create(run, manager,
 				      &manager->threads[manager->workers]) ==
 		    ISC_R_SUCCESS) {
+			char name[16];	/* thread name limit on Linux */
+			snprintf(name, sizeof(name), "isc-worker%04d", i);
+			isc_thread_setname(manager->threads[manager->workers],
+					   name);
 			manager->workers++;
 			started++;
 		}

lib/isc/timer.c

@@ -914,6 +914,7 @@ isc__timermgr_create(isc_mem_t *mctx, isc_timermgr_t **managerp) {
 						ISC_MSG_FAILED, "failed"));
 		return (ISC_R_UNEXPECTED);
 	}
+	isc_thread_setname(manager->thread, "isc-timer");
 #endif
 #ifdef USE_SHARED_MANAGER
 	manager->refs = 1;

lib/isc/unix/socket.c

@@ -4772,6 +4772,7 @@ isc__socketmgr_create2(isc_mem_t *mctx, isc_socketmgr_t **managerp,
 		result = ISC_R_UNEXPECTED;
 		goto cleanup;
 	}
+	isc_thread_setname(manager->watcher, "isc-socket");
 #endif /* USE_WATCHER_THREAD */
 	isc_mem_attach(mctx, &manager->mctx);
 

lib/isc/win32/include/isc/thread.h

@@ -74,6 +74,9 @@ isc_thread_join(isc_thread_t, isc_threadresult_t *);
 void
 isc_thread_setconcurrency(unsigned int level);
 
+void
+isc_thread_setname(isc_thread_t, const char *);
+
 int
 isc_thread_key_create(isc_thread_key_t *key, void (*func)(void *));
 

lib/isc/win32/libisc.def.in

@@ -705,6 +705,7 @@ isc_thread_key_delete
 isc_thread_key_getspecific
 isc_thread_key_setspecific
 isc_thread_setconcurrency
+isc_thread_setname
 isc_time_add
 isc_time_compare
 isc_time_formatISO8601

lib/isc/win32/thread.c

@@ -58,6 +58,12 @@ isc_thread_setconcurrency(unsigned int level) {
 	 */
 }
 
+void
+isc_thread_setname(isc_thread_t thread, const char *name) {
+	UNUSED(thread);
+	UNUSED(name);
+}
+
 void *
 isc_thread_key_getspecific(isc_thread_key_t key) {
 	return(TlsGetValue(key));