* [PATCH] mwrap 2.0.0 mwrap - LD_PRELOAD malloc wrapper for Ruby
@ 2018-07-20 9:25 5% Eric Wong
0 siblings, 0 replies; 3+ results
From: Eric Wong @ 2018-07-20 9:25 UTC (permalink / raw)
To: ruby-talk, mwrap-public
mwrap is designed to answer the question:
Which lines of Ruby are hitting malloc the most?
mwrap wraps all malloc-family calls to trace the Ruby source
location of such calls and bytes allocated at each callsite.
As of mwrap 2.0.0, it can also function as a leak detector
and show live allocations at every call site. Depending on
your application and workload, the overhead is roughly a 50%
increase memory and runtime.
It works best for allocations under GVL, but tries to track
numeric caller addresses for allocations made without GVL so you
can get an idea of how much memory usage certain extensions and
native libraries use.
It requires the concurrent lock-free hash table from the
Userspace RCU project: https://liburcu.org/
It does not require recompiling or rebuilding Ruby, but only
supports Ruby trunk (2.6.0dev+) on a few platforms:
* GNU/Linux
* FreeBSD (tested 11.1)
It may work on NetBSD, OpenBSD and DragonFly BSD.
Changes in 2.0.0:
This release includes significant changes to track live
allocations and frees. It can find memory leaks from malloc
with less overhead than valgrind's leakchecker and there is a
new Rack endpoint (MwrapRack) which can display live allocation
stats.
API additions:
* Mwrap#[] - https://80x24.org/mwrap/Mwrap.html#method-c-5B-5D
* Mwrap::SourceLocation - https://80x24.org/mwrap/Mwrap/SourceLocation.html
* MwrapRack - https://80x24.org/mwrap/MwrapRack.html
Incompatible changes:
* Mwrap.clear now an alias to Mwrap.reset; as it's unsafe
to implement the new Mwrap#[] API otherwise:
https://80x24.org/mwrap-public/20180716211933.5835-12-e@80x24.org/
26 changes since v1.0.0:
README: improve usage example
MANIFEST: add .document
add benchmark
use __attribute__((weak)) instead of dlsym
Mwrap.dump: do not segfault on invalid IO arg
bin/mwrap: support LISTEN_FDS env from systemd
support per-allocation headers for per-alloc tracking
mwrap: use malloc to do our own memalign
hold RCU read lock to insert each allocation
realloc: do not copy if allocation failed
internal_memalign: do not assume real_malloc succeeds
ensure ENOMEM is preserved in errno when appropriate
memalign: check alignment on all public functions
reduce stack usage from file names
resolve real_malloc earlier for C++ programs
allow analyzing live allocations via Mwrap[location]
alias Mwrap.clear to Mwrap.reset
implement accessors for SourceLocation
mwrap_aref: quiet -Wshorten-64-to-32 warning
fixes for FreeBSD 11.1...
use memrchr to extract address under glibc
do not track allocations for constructor and Init_
disable memalign tracking by default
support Mwrap.quiet to temporarily disable allocation tracking
mwrap_rack: Rack app to track live allocations
documentation updates for 2.0.0 release
^ permalink raw reply [relevance 5%]
* [PATCH 11/19] alias Mwrap.clear to Mwrap.reset
2018-07-16 21:19 4% [PATCH 0/19] the heavy version of mwrap Eric Wong
@ 2018-07-16 21:19 7% ` Eric Wong
0 siblings, 0 replies; 3+ results
From: Eric Wong @ 2018-07-16 21:19 UTC (permalink / raw)
To: mwrap-public
It is not safe to use the new Mwrap[] method with Mwrap.clear,
and the rcu_head overhead in src_loc structs was not worth it.
---
ext/mwrap/mwrap.c | 56 ++++++++---------------------------------------
1 file changed, 9 insertions(+), 47 deletions(-)
diff --git a/ext/mwrap/mwrap.c b/ext/mwrap/mwrap.c
index 1216c44..729e3a8 100644
--- a/ext/mwrap/mwrap.c
+++ b/ext/mwrap/mwrap.c
@@ -185,7 +185,6 @@ static int has_ec_p(void)
/* allocated via real_malloc/real_free */
struct src_loc {
- struct rcu_head rcu_head;
pthread_mutex_t *mtx;
size_t calls;
size_t total;
@@ -667,49 +666,6 @@ static VALUE mwrap_dump(int argc, VALUE * argv, VALUE mod)
return Qnil;
}
-static void
-free_src_loc(struct rcu_head *head)
-{
- struct src_loc *l = caa_container_of(head, struct src_loc, rcu_head);
- real_free(l);
-}
-
-static void *totals_clear(void *ign)
-{
- struct cds_lfht *new, *old;
- struct cds_lfht_iter iter;
- struct src_loc *l;
-
- new = lfht_new();
- rcu_read_lock();
- old = rcu_dereference(totals);
- rcu_assign_pointer(totals, new);
- cds_lfht_for_each_entry(old, &iter, l, hnode) {
- cds_lfht_del(old, &l->hnode);
- call_rcu(&l->rcu_head, free_src_loc);
- }
- rcu_read_unlock();
-
- synchronize_rcu(); /* ensure totals points to new */
- cds_lfht_destroy(old, NULL);
- return 0;
-}
-
-/*
- * call-seq:
- *
- * Mwrap.clear -> nil
- *
- * Atomically replaces the totals table and destroys the old one.
- * This resets all statistics. It is more expensive than `Mwrap.reset'
- * as new allocations will need to be made to repopulate the new table.
- */
-static VALUE mwrap_clear(VALUE mod)
-{
- rb_thread_call_without_gvl(totals_clear, 0, 0, 0);
- return Qnil;
-}
-
static void *totals_reset(void *ign)
{
struct cds_lfht *t;
@@ -732,8 +688,8 @@ static void *totals_reset(void *ign)
* Mwrap.reset -> nil
*
* Resets the the total tables by zero-ing all counters.
- * This resets all statistics and is less costly than `Mwrap.clear'
- * but is not an atomic operation.
+ * This resets all statistics. This is not an atomic operation
+ * as other threads (outside of GVL) may increment counters.
*/
static VALUE mwrap_reset(VALUE mod)
{
@@ -741,6 +697,12 @@ static VALUE mwrap_reset(VALUE mod)
return Qnil;
}
+/* :nodoc: */
+static VALUE mwrap_clear(VALUE mod)
+{
+ return mwrap_reset(mod);
+}
+
static VALUE rcu_unlock_ensure(VALUE ignored)
{
rcu_read_unlock();
@@ -944,8 +906,8 @@ void Init_mwrap(void)
cSrcLoc = rb_define_class_under(mod, "SourceLocation", rb_cObject);
rb_define_singleton_method(mod, "dump", mwrap_dump, -1);
- rb_define_singleton_method(mod, "clear", mwrap_clear, 0);
rb_define_singleton_method(mod, "reset", mwrap_reset, 0);
+ rb_define_singleton_method(mod, "clear", mwrap_clear, 0);
rb_define_singleton_method(mod, "each", mwrap_each, -1);
rb_define_singleton_method(mod, "[]", mwrap_aref, 1);
rb_define_method(cSrcLoc, "each", src_loc_each, 0);
--
EW
^ permalink raw reply related [relevance 7%]
* [PATCH 0/19] the heavy version of mwrap
@ 2018-07-16 21:19 4% Eric Wong
2018-07-16 21:19 7% ` [PATCH 11/19] alias Mwrap.clear to Mwrap.reset Eric Wong
0 siblings, 1 reply; 3+ results
From: Eric Wong @ 2018-07-16 21:19 UTC (permalink / raw)
To: mwrap-public
TL;DR: live demo of the new features running inside a Rack app:
https://80x24.org/MWRAP/each/2000
The following changes since commit 834de3bc0da4af53535d5c9d4975e546df9fb186:
bin/mwrap: support LISTEN_FDS env from systemd (2018-07-16 19:33:12 +0000)
are available in the Git repository at:
https://80x24.org/mwrap.git heavy
for you to fetch changes up to c432e3ad30aa247dbac8575af87b0c594365d3fd:
mwrap_rack: Rack app to track live allocations (2018-07-16 21:14:13 +0000)
----------------------------------------------------------------
Eric Wong (19):
support per-allocation headers for per-alloc tracking
mwrap: use malloc to do our own memalign
hold RCU read lock to insert each allocation
realloc: do not copy if allocation failed
internal_memalign: do not assume real_malloc succeeds
ensure ENOMEM is preserved in errno when appropriate
memalign: check alignment on all public functions
reduce stack usage from file names
resolve real_malloc earlier for C++ programs
allow analyzing live allocations via Mwrap[location]
alias Mwrap.clear to Mwrap.reset
implement accessors for SourceLocation
mwrap_aref: quiet -Wshorten-64-to-32 warning
fixes for FreeBSD 11.1...
use memrchr to extract address under glibc
do not track allocations for constructor and Init_
disable memalign tracking by default
support Mwrap.quiet to temporarily disable allocation tracking
mwrap_rack: Rack app to track live allocations
ext/mwrap/extconf.rb | 15 +
ext/mwrap/mwrap.c | 792 +++++++++++++++++++++++++++++++++++++++++++--------
lib/mwrap_rack.rb | 105 +++++++
test/test_mwrap.rb | 113 ++++++++
4 files changed, 901 insertions(+), 124 deletions(-)
create mode 100644 lib/mwrap_rack.rb
^ permalink raw reply [relevance 4%]
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2018-07-16 21:19 7% ` [PATCH 11/19] alias Mwrap.clear to Mwrap.reset Eric Wong
2018-07-20 9:25 5% [PATCH] mwrap 2.0.0 mwrap - LD_PRELOAD malloc wrapper for Ruby Eric Wong
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