Add "prof.dump_prefix" to override filename prefixes for dumps.

doc/jemalloc.xml.in

@@ -1344,7 +1344,10 @@ malloc_conf = "xmalloc:true";]]></programlisting>
         set to the empty string, no automatic dumps will occur; this is
         primarily useful for disabling the automatic final heap dump (which
         also disables leak reporting, if enabled).  The default prefix is
-        <filename>jeprof</filename>.</para></listitem>
+        <filename>jeprof</filename>.  This prefix value can be overriden by
+        <link
+        linkend="prof.dump_prefix"><mallctl>prof.dump_prefix</mallctl></link>.
+        </para></listitem>
       </varlistentry>
 
       <varlistentry id="opt.prof_active">
@@ -1423,8 +1426,10 @@ malloc_conf = "xmalloc:true";]]></programlisting>
         <filename>&lt;prefix&gt;.&lt;pid&gt;.&lt;seq&gt;.i&lt;iseq&gt;.heap</filename>,
         where <literal>&lt;prefix&gt;</literal> is controlled by the
         <link
-        linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link>
+        linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link> and
-        option.  By default, interval-triggered profile dumping is disabled
+        <link
+        linkend="prof.dump_prefix"><mallctl>prof.dump_prefix</mallctl></link>
+        options.  By default, interval-triggered profile dumping is disabled
         (encoded as -1).
         </para></listitem>
       </varlistentry>
@@ -1456,8 +1461,10 @@ malloc_conf = "xmalloc:true";]]></programlisting>
         usage to a file named according to the pattern
         <filename>&lt;prefix&gt;.&lt;pid&gt;.&lt;seq&gt;.f.heap</filename>,
         where <literal>&lt;prefix&gt;</literal> is controlled by the <link
-        linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link>
+        linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link> and
-        option.  Note that <function>atexit()</function> may allocate
+        <link
+        linkend="prof.dump_prefix"><mallctl>prof.dump_prefix</mallctl></link>
+        options.  Note that <function>atexit()</function> may allocate
         memory during application initialization and then deadlock internally
         when jemalloc in turn calls <function>atexit()</function>, so
         this option is not universally usable (though the application can
@@ -2224,8 +2231,25 @@ struct extent_hooks_s {
         <filename>&lt;prefix&gt;.&lt;pid&gt;.&lt;seq&gt;.m&lt;mseq&gt;.heap</filename>,
         where <literal>&lt;prefix&gt;</literal> is controlled by the
         <link
+        linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link> and
+        <link
+        linkend="prof.dump_prefix"><mallctl>prof.dump_prefix</mallctl></link>
+        options.</para></listitem>
+      </varlistentry>
+
+      <varlistentry id="prof.dump_prefix">
+        <term>
+          <mallctl>prof.dump_prefix</mallctl>
+          (<type>const char *</type>)
+          <literal>-w</literal>
+          [<option>--enable-prof</option>]
+        </term>
+        <listitem><para>Set the filename prefix for profile dumps. See
+        <link
         linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link>
-        option.</para></listitem>
+        for the default setting.  This can be useful to differentiate profile
+        dumps such as from forked processes.
+        </para></listitem>
       </varlistentry>
 
       <varlistentry id="prof.gdump">
@@ -2240,8 +2264,10 @@ struct extent_hooks_s {
         dumped to files named according to the pattern
         <filename>&lt;prefix&gt;.&lt;pid&gt;.&lt;seq&gt;.u&lt;useq&gt;.heap</filename>,
         where <literal>&lt;prefix&gt;</literal> is controlled by the <link
-        linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link>
+        linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link> and
-        option.</para></listitem>
+        <link
+        linkend="prof.dump_prefix"><mallctl>prof.dump_prefix</mallctl></link>
+        options.</para></listitem>
       </varlistentry>
 
       <varlistentry id="prof.reset">

include/jemalloc/internal/ctl.h

@@ -103,6 +103,7 @@ bool ctl_boot(void);
 void ctl_prefork(tsdn_t *tsdn);
 void ctl_postfork_parent(tsdn_t *tsdn);
 void ctl_postfork_child(tsdn_t *tsdn);
+void ctl_mtx_assert_held(tsdn_t *tsdn);
 
 #define xmallctl(name, oldp, oldlenp, newp, newlen) do {		\
 	if (je_mallctl(name, oldp, oldlenp, newp, newlen)		\

include/jemalloc/internal/prof_externs.h

@@ -72,10 +72,12 @@ void prof_cnt_all(uint64_t *curobjs, uint64_t *curbytes, uint64_t *accumobjs,
     uint64_t *accumbytes);
 #endif
 int prof_getpid(void);
+void prof_get_default_filename(tsdn_t *tsdn, char *filename, uint64_t ind);
 bool prof_accum_init(tsdn_t *tsdn, prof_accum_t *prof_accum);
 void prof_idump(tsdn_t *tsdn);
 bool prof_mdump(tsd_t *tsd, const char *filename);
 void prof_gdump(tsdn_t *tsdn);
+bool prof_dump_prefix_set(tsdn_t *tsdn, const char *prefix);
 
 void prof_bt_hash(const void *key, size_t r_hash[2]);
 bool prof_bt_keycomp(const void *k1, const void *k2);

include/jemalloc/internal/prof_types.h

@@ -53,4 +53,11 @@ typedef struct prof_tdata_s prof_tdata_t;
 #define PROF_TDATA_STATE_PURGATORY	((prof_tdata_t *)(uintptr_t)2)
 #define PROF_TDATA_STATE_MAX		PROF_TDATA_STATE_PURGATORY
 
+/* Minimize memory bloat for non-prof builds. */
+#ifdef JEMALLOC_PROF
+#define PROF_DUMP_FILENAME_LEN (PATH_MAX + 1)
+#else
+#define PROF_DUMP_FILENAME_LEN 1
+#endif
+
 #endif /* JEMALLOC_INTERNAL_PROF_TYPES_H */

src/ctl.c

@@ -148,6 +148,7 @@ CTL_PROTO(prof_thread_active_init)
 CTL_PROTO(prof_active)
 CTL_PROTO(prof_dump)
 CTL_PROTO(prof_gdump)
+CTL_PROTO(prof_dump_prefix)
 CTL_PROTO(prof_reset)
 CTL_PROTO(prof_interval)
 CTL_PROTO(lg_prof_sample)
@@ -413,6 +414,7 @@ static const ctl_named_node_t	prof_node[] = {
 	{NAME("active"),	CTL(prof_active)},
 	{NAME("dump"),		CTL(prof_dump)},
 	{NAME("gdump"),		CTL(prof_gdump)},
+	{NAME("dump_prefix"),	CTL(prof_dump_prefix)},
 	{NAME("reset"),		CTL(prof_reset)},
 	{NAME("interval"),	CTL(prof_interval)},
 	{NAME("lg_sample"),	CTL(lg_prof_sample)},
@@ -1416,6 +1418,11 @@ ctl_postfork_child(tsdn_t *tsdn) {
 	malloc_mutex_postfork_child(tsdn, &ctl_mtx);
 }
 
+void
+ctl_mtx_assert_held(tsdn_t *tsdn) {
+	malloc_mutex_assert_owner(tsdn, &ctl_mtx);
+}
+
 /******************************************************************************/
 /* *_ctl() functions. */
 
@@ -2720,6 +2727,26 @@ label_return:
 	return ret;
 }
 
+static int
+prof_dump_prefix_ctl(tsd_t *tsd, const size_t *mib, size_t miblen,
+    void *oldp, size_t *oldlenp, void *newp, size_t newlen) {
+	int ret;
+	const char *prefix = NULL;
+
+	if (!config_prof) {
+		return ENOENT;
+	}
+
+	malloc_mutex_lock(tsd_tsdn(tsd), &ctl_mtx);
+	WRITEONLY();
+	WRITE(prefix, const char *);
+
+	ret = prof_dump_prefix_set(tsd_tsdn(tsd), prefix) ? EFAULT : 0;
+label_return:
+	malloc_mutex_unlock(tsd_tsdn(tsd), &ctl_mtx);
+	return ret;
+}
+
 static int
 prof_reset_ctl(tsd_t *tsd, const size_t *mib, size_t miblen,
     void *oldp, size_t *oldlenp, void *newp, size_t newlen) {

src/prof.c

@@ -2,6 +2,7 @@
 #include "jemalloc/internal/jemalloc_preamble.h"
 #include "jemalloc/internal/jemalloc_internal_includes.h"
 
+#include "jemalloc/internal/ctl.h"
 #include "jemalloc/internal/assert.h"
 #include "jemalloc/internal/mutex.h"
 
@@ -41,12 +42,7 @@ bool		opt_prof_gdump = false;
 bool		opt_prof_final = false;
 bool		opt_prof_leak = false;
 bool		opt_prof_accum = false;
-char		opt_prof_prefix[
+char		opt_prof_prefix[PROF_DUMP_FILENAME_LEN];
-    /* Minimize memory bloat for non-prof builds. */
-#ifdef JEMALLOC_PROF
-    PATH_MAX +
-#endif
-    1];
 
 /*
  * Initialized as opt_prof_active, and accessed via
@@ -106,6 +102,7 @@ static uint64_t		prof_dump_mseq;
 static uint64_t		prof_dump_useq;
 
 malloc_mutex_t	prof_dump_mtx;
+static char	*prof_dump_prefix = NULL;
 
 /* Do not dump any profiles until bootstrapping is complete. */
 bool			prof_booted = false;
@@ -514,26 +511,53 @@ prof_getpid(void) {
 #endif
 }
 
+static const char *
+prof_dump_prefix_get(tsdn_t* tsdn) {
+	malloc_mutex_assert_owner(tsdn, &prof_dump_filename_mtx);
+
+	return prof_dump_prefix == NULL ? opt_prof_prefix : prof_dump_prefix;
+}
+
+static bool
+prof_dump_prefix_is_empty(tsdn_t *tsdn) {
+	malloc_mutex_lock(tsdn, &prof_dump_filename_mtx);
+	bool ret = (prof_dump_prefix_get(tsdn)[0] == '\0');
+	malloc_mutex_unlock(tsdn, &prof_dump_filename_mtx);
+	return ret;
+}
+
 #define DUMP_FILENAME_BUFSIZE	(PATH_MAX + 1)
 #define VSEQ_INVALID		UINT64_C(0xffffffffffffffff)
 static void
-prof_dump_filename(char *filename, char v, uint64_t vseq) {
+prof_dump_filename(tsd_t *tsd, char *filename, char v, uint64_t vseq) {
 	cassert(config_prof);
 
+	assert(tsd_reentrancy_level_get(tsd) == 0);
+	const char *prof_prefix = prof_dump_prefix_get(tsd_tsdn(tsd));
+
 	if (vseq != VSEQ_INVALID) {
 	        /* "<prefix>.<pid>.<seq>.v<vseq>.heap" */
 		malloc_snprintf(filename, DUMP_FILENAME_BUFSIZE,
 		    "%s.%d.%"FMTu64".%c%"FMTu64".heap",
-		    opt_prof_prefix, prof_getpid(), prof_dump_seq, v, vseq);
+		    prof_prefix, prof_getpid(), prof_dump_seq, v, vseq);
 	} else {
 	        /* "<prefix>.<pid>.<seq>.<v>.heap" */
 		malloc_snprintf(filename, DUMP_FILENAME_BUFSIZE,
 		    "%s.%d.%"FMTu64".%c.heap",
-		    opt_prof_prefix, prof_getpid(), prof_dump_seq, v);
+		    prof_prefix, prof_getpid(), prof_dump_seq, v);
 	}
 	prof_dump_seq++;
 }
 
+void
+prof_get_default_filename(tsdn_t *tsdn, char *filename, uint64_t ind) {
+	malloc_mutex_lock(tsdn, &prof_dump_filename_mtx);
+	malloc_snprintf(filename, PROF_DUMP_FILENAME_LEN,
+	    "%s.%d.%"FMTu64".json", prof_dump_prefix_get(tsdn), prof_getpid(),
+	    ind);
+	malloc_mutex_unlock(tsdn, &prof_dump_filename_mtx);
+}
+
 static void
 prof_fdump(void) {
 	tsd_t *tsd;
@@ -541,16 +565,16 @@ prof_fdump(void) {
 
 	cassert(config_prof);
 	assert(opt_prof_final);
-	assert(opt_prof_prefix[0] != '\0');
 
 	if (!prof_booted) {
 		return;
 	}
 	tsd = tsd_fetch();
 	assert(tsd_reentrancy_level_get(tsd) == 0);
+	assert(!prof_dump_prefix_is_empty(tsd_tsdn(tsd)));
 
 	malloc_mutex_lock(tsd_tsdn(tsd), &prof_dump_filename_mtx);
-	prof_dump_filename(filename, 'f', VSEQ_INVALID);
+	prof_dump_filename(tsd, filename, 'f', VSEQ_INVALID);
 	malloc_mutex_unlock(tsd_tsdn(tsd), &prof_dump_filename_mtx);
 	prof_dump(tsd, false, filename, opt_prof_leak);
 }
@@ -571,6 +595,31 @@ prof_accum_init(tsdn_t *tsdn, prof_accum_t *prof_accum) {
 	return false;
 }
 
+bool
+prof_dump_prefix_set(tsdn_t *tsdn, const char *prefix) {
+	cassert(config_prof);
+	ctl_mtx_assert_held(tsdn);
+	malloc_mutex_lock(tsdn, &prof_dump_filename_mtx);
+	if (prof_dump_prefix == NULL) {
+		malloc_mutex_unlock(tsdn, &prof_dump_filename_mtx);
+		/* Everything is still guarded by ctl_mtx. */
+		char *buffer = base_alloc(tsdn, b0get(), PROF_DUMP_FILENAME_LEN,
+		    QUANTUM);
+		if (buffer == NULL) {
+			return true;
+		}
+		malloc_mutex_lock(tsdn, &prof_dump_filename_mtx);
+		prof_dump_prefix = buffer;
+	}
+	assert(prof_dump_prefix != NULL);
+
+	strncpy(prof_dump_prefix, prefix, PROF_DUMP_FILENAME_LEN - 1);
+	prof_dump_prefix[PROF_DUMP_FILENAME_LEN - 1] = '\0';
+	malloc_mutex_unlock(tsdn, &prof_dump_filename_mtx);
+
+	return false;
+}
+
 void
 prof_idump(tsdn_t *tsdn) {
 	tsd_t *tsd;
@@ -595,15 +644,17 @@ prof_idump(tsdn_t *tsdn) {
 		return;
 	}
 
-	if (opt_prof_prefix[0] != '\0') {
-		char filename[PATH_MAX + 1];
 	malloc_mutex_lock(tsd_tsdn(tsd), &prof_dump_filename_mtx);
-		prof_dump_filename(filename, 'i', prof_dump_iseq);
+	if (prof_dump_prefix_get(tsd_tsdn(tsd))[0] == '\0') {
+		malloc_mutex_unlock(tsd_tsdn(tsd), &prof_dump_filename_mtx);
+		return;
+	}
+	char filename[PATH_MAX + 1];
+	prof_dump_filename(tsd, filename, 'i', prof_dump_iseq);
 	prof_dump_iseq++;
 	malloc_mutex_unlock(tsd_tsdn(tsd), &prof_dump_filename_mtx);
 	prof_dump(tsd, false, filename, false);
 }
-}
 
 bool
 prof_mdump(tsd_t *tsd, const char *filename) {
@@ -616,11 +667,12 @@ prof_mdump(tsd_t *tsd, const char *filename) {
 	char filename_buf[DUMP_FILENAME_BUFSIZE];
 	if (filename == NULL) {
 		/* No filename specified, so automatically generate one. */
-		if (opt_prof_prefix[0] == '\0') {
+		malloc_mutex_lock(tsd_tsdn(tsd), &prof_dump_filename_mtx);
+		if (prof_dump_prefix_get(tsd_tsdn(tsd))[0] == '\0') {
+			malloc_mutex_unlock(tsd_tsdn(tsd), &prof_dump_filename_mtx);
 			return true;
 		}
-		malloc_mutex_lock(tsd_tsdn(tsd), &prof_dump_filename_mtx);
+		prof_dump_filename(tsd, filename_buf, 'm', prof_dump_mseq);
-		prof_dump_filename(filename_buf, 'm', prof_dump_mseq);
 		prof_dump_mseq++;
 		malloc_mutex_unlock(tsd_tsdn(tsd), &prof_dump_filename_mtx);
 		filename = filename_buf;
@@ -652,15 +704,17 @@ prof_gdump(tsdn_t *tsdn) {
 		return;
 	}
 
-	if (opt_prof_prefix[0] != '\0') {
-		char filename[DUMP_FILENAME_BUFSIZE];
 	malloc_mutex_lock(tsdn, &prof_dump_filename_mtx);
-		prof_dump_filename(filename, 'u', prof_dump_useq);
+	if (prof_dump_prefix_get(tsdn)[0] == '\0') {
+		malloc_mutex_unlock(tsdn, &prof_dump_filename_mtx);
+		return;
+	}
+	char filename[DUMP_FILENAME_BUFSIZE];
+	prof_dump_filename(tsd, filename, 'u', prof_dump_useq);
 	prof_dump_useq++;
 	malloc_mutex_unlock(tsdn, &prof_dump_filename_mtx);
 	prof_dump(tsd, false, filename, false);
 }
-}
 
 static uint64_t
 prof_thr_uid_alloc(tsdn_t *tsdn) {

src/prof_log.c

@@ -405,7 +405,6 @@ prof_log_start(tsdn_t *tsdn, const char *filename) {
 	}
 
 	bool ret = false;
-	size_t buf_size = PATH_MAX + 1;
 
 	malloc_mutex_lock(tsdn, &log_mtx);
 
@@ -413,11 +412,10 @@ prof_log_start(tsdn_t *tsdn, const char *filename) {
 		ret = true;
 	} else if (filename == NULL) {
 		/* Make default name. */
-		malloc_snprintf(log_filename, buf_size, "%s.%d.%"FMTu64".json",
+		prof_get_default_filename(tsdn, log_filename, log_seq);
-		    opt_prof_prefix, prof_getpid(), log_seq);
 		log_seq++;
 		prof_logging_state = prof_logging_state_started;
-	} else if (strlen(filename) >= buf_size) {
+	} else if (strlen(filename) >= PROF_DUMP_FILENAME_LEN) {
 		ret = true;
 	} else {
 		strcpy(log_filename, filename);

test/unit/prof_idump.c

@@ -1,5 +1,7 @@
 #include "test/jemalloc_test.h"
 
+#define TEST_PREFIX "test_prefix"
+
 static bool did_prof_dump_open;
 
 static int
@@ -8,6 +10,10 @@ prof_dump_open_intercept(bool propagate_err, const char *filename) {
 
 	did_prof_dump_open = true;
 
+	const char filename_prefix[] = TEST_PREFIX ".";
+	assert_d_eq(strncmp(filename_prefix, filename, sizeof(filename_prefix)
+	    - 1), 0, "Dump file name should start with \"" TEST_PREFIX ".\"");
+
 	fd = open("/dev/null", O_WRONLY);
 	assert_d_ne(fd, -1, "Unexpected open() failure");
 
@@ -18,9 +24,16 @@ TEST_BEGIN(test_idump) {
 	bool active;
 	void *p;
 
+	const char *dump_prefix = TEST_PREFIX;
+
 	test_skip_if(!config_prof);
 
 	active = true;
+
+	assert_d_eq(mallctl("prof.dump_prefix", NULL, NULL,
+	    (void *)&dump_prefix, sizeof(dump_prefix)), 0,
+	    "Unexpected mallctl failure while overwriting dump prefix");
+
 	assert_d_eq(mallctl("prof.active", NULL, NULL, (void *)&active,
 	    sizeof(active)), 0,
 	    "Unexpected mallctl failure while activating profiling");