Add option to fetch system thread name on each prof sample

Makefile.in

@@ -227,6 +227,7 @@ TESTS_UNIT := \
 	$(srcroot)test/unit/prof_reset.c \
 	$(srcroot)test/unit/prof_tctx.c \
 	$(srcroot)test/unit/prof_thread_name.c \
+	$(srcroot)test/unit/prof_use_sys_thread_name.c \
 	$(srcroot)test/unit/ql.c \
 	$(srcroot)test/unit/qr.c \
 	$(srcroot)test/unit/rb.c \

include/jemalloc/internal/prof_externs.h

@@ -28,6 +28,9 @@ extern char opt_prof_prefix[
 extern ssize_t opt_prof_recent_alloc_max;
 extern malloc_mutex_t prof_recent_alloc_mtx;
 
+/* Whether to use thread name provided by the system or by mallctl. */
+extern bool opt_prof_experimental_use_sys_thread_name;
+
 /* Accessed via prof_active_[gs]et{_unlocked,}(). */
 extern bool prof_active;
 
@@ -59,6 +62,8 @@ void prof_malloc_sample_object(tsd_t *tsd, const void *ptr, size_t size,
 void prof_free_sampled_object(tsd_t *tsd, size_t usize, prof_info_t *prof_info);
 prof_tctx_t *prof_tctx_create(tsd_t *tsd);
 #ifdef JEMALLOC_JET
+typedef int (prof_read_sys_thread_name_t)(char *buf, size_t limit);
+extern prof_read_sys_thread_name_t *JET_MUTABLE prof_read_sys_thread_name;
 size_t prof_tdata_count(void);
 size_t prof_bt_count(void);
 #endif

src/ctl.c

@@ -117,6 +117,7 @@ CTL_PROTO(opt_prof_final)
 CTL_PROTO(opt_prof_leak)
 CTL_PROTO(opt_prof_accum)
 CTL_PROTO(opt_prof_recent_alloc_max)
+CTL_PROTO(opt_prof_experimental_use_sys_thread_name)
 CTL_PROTO(opt_zero_realloc)
 CTL_PROTO(tcache_create)
 CTL_PROTO(tcache_flush)
@@ -353,6 +354,8 @@ static const ctl_named_node_t opt_node[] = {
 	{NAME("prof_leak"),	CTL(opt_prof_leak)},
 	{NAME("prof_accum"),	CTL(opt_prof_accum)},
 	{NAME("prof_recent_alloc_max"), CTL(opt_prof_recent_alloc_max)},
+	{NAME("prof_experimental_use_sys_thread_name"),
+	    CTL(opt_prof_experimental_use_sys_thread_name)},
 	{NAME("zero_realloc"),	CTL(opt_zero_realloc)}
 };
 
@@ -1829,6 +1832,8 @@ CTL_RO_NL_CGEN(config_prof, opt_prof_final, opt_prof_final, bool)
 CTL_RO_NL_CGEN(config_prof, opt_prof_leak, opt_prof_leak, bool)
 CTL_RO_NL_CGEN(config_prof, opt_prof_recent_alloc_max,
     opt_prof_recent_alloc_max, ssize_t)
+CTL_RO_NL_CGEN(config_prof, opt_prof_experimental_use_sys_thread_name,
+    opt_prof_experimental_use_sys_thread_name, bool)
 CTL_RO_NL_GEN(opt_zero_realloc,
     zero_realloc_mode_names[opt_zero_realloc_action], const char *)
 

src/jemalloc.c

@@ -1426,6 +1426,9 @@ malloc_conf_init_helper(sc_data_t *sc_data, unsigned bin_shard_sizes[SC_NBINS],
 				CONF_HANDLE_BOOL(opt_prof_log, "prof_log")
 				CONF_HANDLE_SSIZE_T(opt_prof_recent_alloc_max,
 				    "prof_recent_alloc_max", -1, SSIZE_MAX)
+				CONF_HANDLE_BOOL(
+				    opt_prof_experimental_use_sys_thread_name,
+				    "prof_experimental_use_sys_thread_name")
 			}
 			if (config_log) {
 				if (CONF_MATCH("log")) {

src/prof.c

@@ -48,6 +48,7 @@ bool opt_prof_final = false;
 bool opt_prof_leak = false;
 bool opt_prof_accum = false;
 char opt_prof_prefix[PROF_DUMP_FILENAME_LEN];
+bool opt_prof_experimental_use_sys_thread_name = false;
 
 /* Accessed via prof_idump_[accum/rollback](). */
 static counter_accum_t prof_idump_accumulated;
@@ -133,9 +134,101 @@ prof_alloc_rollback(tsd_t *tsd, prof_tctx_t *tctx) {
 	}
 }
 
+static char *
+prof_thread_name_alloc(tsdn_t *tsdn, const char *thread_name) {
+	char *ret;
+	size_t size;
+
+	if (thread_name == NULL) {
+		return NULL;
+	}
+
+	size = strlen(thread_name) + 1;
+	if (size == 1) {
+		return "";
+	}
+
+	ret = iallocztm(tsdn, size, sz_size2index(size), false, NULL, true,
+	    arena_get(TSDN_NULL, 0, true), true);
+	if (ret == NULL) {
+		return NULL;
+	}
+	memcpy(ret, thread_name, size);
+	return ret;
+}
+
+static int
+prof_thread_name_set_impl(tsd_t *tsd, const char *thread_name) {
+	assert(tsd_reentrancy_level_get(tsd) == 0);
+
+	prof_tdata_t *tdata;
+	unsigned i;
+	char *s;
+
+	tdata = prof_tdata_get(tsd, true);
+	if (tdata == NULL) {
+		return EAGAIN;
+	}
+
+	/* Validate input. */
+	if (thread_name == NULL) {
+		return EFAULT;
+	}
+	for (i = 0; thread_name[i] != '\0'; i++) {
+		char c = thread_name[i];
+		if (!isgraph(c) && !isblank(c)) {
+			return EFAULT;
+		}
+	}
+
+	s = prof_thread_name_alloc(tsd_tsdn(tsd), thread_name);
+	if (s == NULL) {
+		return EAGAIN;
+	}
+
+	if (tdata->thread_name != NULL) {
+		idalloctm(tsd_tsdn(tsd), tdata->thread_name, NULL, NULL, true,
+		    true);
+		tdata->thread_name = NULL;
+	}
+	if (strlen(s) > 0) {
+		tdata->thread_name = s;
+	}
+	return 0;
+}
+
+static int
+prof_read_sys_thread_name_impl(char *buf, size_t limit) {
+#ifdef JEMALLOC_HAVE_PTHREAD_SETNAME_NP
+	return pthread_getname_np(pthread_self(), buf, limit);
+#else
+	return ENOSYS;
+#endif
+}
+#ifdef JEMALLOC_JET
+prof_read_sys_thread_name_t *JET_MUTABLE prof_read_sys_thread_name =
+    prof_read_sys_thread_name_impl;
+#else
+#define prof_read_sys_thread_name prof_read_sys_thread_name_impl
+#endif
+
+static void
+prof_fetch_sys_thread_name(tsd_t *tsd) {
+#define THREAD_NAME_MAX_LEN 16
+	char buf[THREAD_NAME_MAX_LEN];
+	if (!prof_read_sys_thread_name(buf, THREAD_NAME_MAX_LEN)) {
+		prof_thread_name_set_impl(tsd, buf);
+	}
+#undef THREAD_NAME_MAX_LEN
+}
+
 void
 prof_malloc_sample_object(tsd_t *tsd, const void *ptr, size_t size,
     size_t usize, prof_tctx_t *tctx) {
+	if (opt_prof_experimental_use_sys_thread_name) {
+		prof_fetch_sys_thread_name(tsd);
+	}
+
 	edata_t *edata = emap_edata_lookup(tsd_tsdn(tsd), &emap_global, ptr);
 	prof_info_set(tsd, edata, tctx);
 
@@ -710,29 +803,6 @@ prof_tdata_init(tsd_t *tsd) {
 	    NULL, prof_thread_active_init_get(tsd_tsdn(tsd)), false);
 }
 
-static char *
-prof_thread_name_alloc(tsdn_t *tsdn, const char *thread_name) {
-	char *ret;
-	size_t size;
-
-	if (thread_name == NULL) {
-		return NULL;
-	}
-
-	size = strlen(thread_name) + 1;
-	if (size == 1) {
-		return "";
-	}
-
-	ret = iallocztm(tsdn, size, sz_size2index(size), false, NULL, true,
-	    arena_get(TSDN_NULL, 0, true), true);
-	if (ret == NULL) {
-		return NULL;
-	}
-	memcpy(ret, thread_name, size);
-	return ret;
-}
-
 prof_tdata_t *
 prof_tdata_reinit(tsd_t *tsd, prof_tdata_t *tdata) {
 	uint64_t thr_uid = tdata->thr_uid;
@@ -799,42 +869,11 @@ prof_thread_name_get(tsd_t *tsd) {
 
 int
 prof_thread_name_set(tsd_t *tsd, const char *thread_name) {
-	assert(tsd_reentrancy_level_get(tsd) == 0);
-
-	prof_tdata_t *tdata;
-	unsigned i;
-	char *s;
-
-	tdata = prof_tdata_get(tsd, true);
-	if (tdata == NULL) {
-		return EAGAIN;
+	if (opt_prof_experimental_use_sys_thread_name) {
+		return ENOENT;
+	} else {
+		return prof_thread_name_set_impl(tsd, thread_name);
 	}
-
-	/* Validate input. */
-	if (thread_name == NULL) {
-		return EFAULT;
-	}
-	for (i = 0; thread_name[i] != '\0'; i++) {
-		char c = thread_name[i];
-		if (!isgraph(c) && !isblank(c)) {
-			return EFAULT;
-		}
-	}
-
-	s = prof_thread_name_alloc(tsd_tsdn(tsd), thread_name);
-	if (s == NULL) {
-		return EAGAIN;
-	}
-
-	if (tdata->thread_name != NULL) {
-		idalloctm(tsd_tsdn(tsd), tdata->thread_name, NULL, NULL, true,
-		    true);
-		tdata->thread_name = NULL;
-	}
-	if (strlen(s) > 0) {
-		tdata->thread_name = s;
-	}
-	return 0;
 }
 
 bool

test/unit/mallctl.c

@@ -192,6 +192,7 @@ TEST_BEGIN(test_mallctl_opt) {
 	TEST_MALLCTL_OPT(bool, prof_final, prof);
 	TEST_MALLCTL_OPT(bool, prof_leak, prof);
 	TEST_MALLCTL_OPT(ssize_t, prof_recent_alloc_max, prof);
+	TEST_MALLCTL_OPT(bool, prof_experimental_use_sys_thread_name, prof);
 
 #undef TEST_MALLCTL_OPT
 }

test/unit/prof_use_sys_thread_name.c

@@ -0,0 +1,75 @@
+#include "test/jemalloc_test.h"
+
+static const char *test_thread_name = "test_name";
+
+static int
+test_prof_read_sys_thread_name_error(char *buf, size_t limit) {
+	return ENOSYS;
+}
+
+static int
+test_prof_read_sys_thread_name(char *buf, size_t limit) {
+	assert(strlen(test_thread_name) < limit);
+	strncpy(buf, test_thread_name, limit);
+	return 0;
+}
+
+static int
+test_prof_read_sys_thread_name_clear(char *buf, size_t limit) {
+	assert(limit > 0);
+	buf[0] = '\0';
+	return 0;
+}
+
+TEST_BEGIN(test_prof_experimental_use_sys_thread_name) {
+	test_skip_if(!config_prof);
+
+	bool oldval;
+	size_t sz = sizeof(oldval);
+	assert_d_eq(mallctl("opt.prof_experimental_use_sys_thread_name",
+	    &oldval, &sz, NULL,	0), 0, "mallctl failed");
+	assert_true(oldval, "option was not set correctly");
+
+	const char *thread_name;
+	sz = sizeof(thread_name);
+	assert_d_eq(mallctl("thread.prof.name", &thread_name, &sz, NULL, 0), 0,
+	    "mallctl read for thread name should not fail");
+	expect_str_eq(thread_name, "", "Initial thread name should be empty");
+
+	thread_name = test_thread_name;
+	assert_d_eq(mallctl("thread.prof.name", NULL, NULL, &thread_name, sz),
+	    ENOENT, "mallctl write for thread name should fail");
+	assert_ptr_eq(thread_name, test_thread_name,
+	    "Thread name should not be touched");
+
+	prof_read_sys_thread_name = test_prof_read_sys_thread_name_error;
+	void *p = malloc(1);
+	free(p);
+	assert_d_eq(mallctl("thread.prof.name", &thread_name, &sz, NULL, 0), 0,
+	    "mallctl read for thread name should not fail");
+	assert_str_eq(thread_name, "",
+	    "Thread name should stay the same if the system call fails");
+
+	prof_read_sys_thread_name = test_prof_read_sys_thread_name;
+	p = malloc(1);
+	free(p);
+	assert_d_eq(mallctl("thread.prof.name", &thread_name, &sz, NULL, 0), 0,
+	    "mallctl read for thread name should not fail");
+	assert_str_eq(thread_name, test_thread_name,
+	    "Thread name should be changed if the system call succeeds");
+
+	prof_read_sys_thread_name = test_prof_read_sys_thread_name_clear;
+	p = malloc(1);
+	free(p);
+	assert_d_eq(mallctl("thread.prof.name", &thread_name, &sz, NULL, 0), 0,
+	    "mallctl read for thread name should not fail");
+	expect_str_eq(thread_name, "", "Thread name should be updated if the "
+	    "system call returns a different name");
+}
+TEST_END
+
+int
+main(void) {
+	return test(
+	    test_prof_experimental_use_sys_thread_name);
+}

test/unit/prof_use_sys_thread_name.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+
+if [ "x${enable_prof}" = "x1" ] ; then
+  export MALLOC_CONF="prof:true,lg_prof_sample:0,prof_experimental_use_sys_thread_name:true"
+fi