* [ANN] mwrap 2.1.0 mwrap - LD_PRELOAD malloc wrapper for Ruby
@ 2018-08-11 4:31 7% Eric Wong
0 siblings, 0 replies; 2+ results
From: Eric Wong @ 2018-08-11 4:31 UTC (permalink / raw)
To: ruby-talk, mwrap-public
Changes:
mwrap 2.1.0 - heap_page_body struct tracking
This release enables tracking of memalign allocations for
"struct heap_page_body" in the Ruby GC. This can be useful
for tracking deathspans (time between free and re-allocation)
of heap page bodies which can cause fragmentation in some
malloc implementations, including glibc.
The documentation for it is available at:
https://80x24.org/mwrap/Mwrap/HeapPageBody.html
And a live demo runs at:
https://80x24.org/MWRAP/heap_pages
This release also includes global counters for
Mwrap.total_bytes_allocated and Mwrap.total_bytes_freed
10 changes since v2.0.0 (2018-07-20):
add olddoc.yml to generate links in page footers
add .olddoc.yml to MANIFEST
gemspec: use "git describe" output for prereleases
add global counters for total bytes allocated/freed
keep stats for memalign-ed heap_page_body in Ruby
remove "memalign:" MWRAP option
allow dump_heap: mask via MWRAP env
tweak hpb stats destructor output
struct acc: use 64-bit counters
doc: 2.1 pre-release updates
About:
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.
Mailing list and archives:
https://80x24.org/mwrap-public/
nntp://80x24.org/inbox.comp.lang.ruby.mwrap
mailto:mwrap-public@80x24.org (no HTML mail, please)
Note: I might not be able answer questions about this for a few days.
git clone https://80x24.org/mwrap.git
homepage + rdoc: https://80x24.org/mwrap/
^ permalink raw reply [relevance 7%]
* [PATCH] keep stats for memalign-ed heap_page_body in Ruby
@ 2018-08-10 6:49 4% Eric Wong
0 siblings, 0 replies; 2+ results
From: Eric Wong @ 2018-08-10 6:49 UTC (permalink / raw)
To: mwrap-public; +Cc: Eric Wong
free-ing and calling posix_memalign again can cause
fragmentation in glibc malloc (at least):
https://sourceware.org/bugzilla/show_bug.cgi?id=14581
Add statistics to track lifetimes and deathtimes (time between
free and resurrection via posix_memalign).
---
ext/mwrap/mwrap.c | 261 ++++++++++++++++++++++++++++++++++++++++++---
lib/mwrap_rack.rb | 53 ++++++++-
test/test_mwrap.rb | 29 +++++
3 files changed, 327 insertions(+), 16 deletions(-)
diff --git a/ext/mwrap/mwrap.c b/ext/mwrap/mwrap.c
index 9bb44d0..b2d169f 100644
--- a/ext/mwrap/mwrap.c
+++ b/ext/mwrap/mwrap.c
@@ -30,6 +30,7 @@ extern void * __attribute__((weak)) ruby_current_execution_context_ptr;
extern void * __attribute__((weak)) ruby_current_vm_ptr; /* for rb_gc_count */
extern size_t __attribute__((weak)) rb_gc_count(void);
extern VALUE __attribute__((weak)) rb_cObject;
+extern VALUE __attribute__((weak)) rb_eTypeError;
extern VALUE __attribute__((weak)) rb_yield(VALUE);
static size_t total_bytes_inc, total_bytes_dec;
@@ -37,6 +38,16 @@ static size_t total_bytes_inc, total_bytes_dec;
/* true for glibc/dlmalloc/ptmalloc, not sure about jemalloc */
#define ASSUMED_MALLOC_ALIGNMENT (sizeof(void *) * 2)
+/* match values in Ruby gc.c */
+#define HEAP_PAGE_ALIGN_LOG 14
+enum {
+ HEAP_PAGE_ALIGN = (1UL << HEAP_PAGE_ALIGN_LOG),
+ REQUIRED_SIZE_BY_MALLOC = (sizeof(size_t) * 5),
+ HEAP_PAGE_SIZE = (HEAP_PAGE_ALIGN - REQUIRED_SIZE_BY_MALLOC)
+};
+
+#define IS_HEAP_PAGE_BODY ((struct src_loc *)-1)
+
int __attribute__((weak)) ruby_thread_has_gvl_p(void)
{
return 0;
@@ -213,6 +224,32 @@ static int has_ec_p(void)
ruby_current_execution_context_ptr);
}
+struct acc {
+ size_t nr;
+ size_t min;
+ size_t max;
+ double m2;
+ double mean;
+};
+
+#define ACC_INIT(name) { .nr=0, .min=SIZE_MAX, .max=0, .m2=0, .mean=0 }
+
+/* for tracking 16K-aligned heap page bodies (protected by GVL) */
+struct {
+ pthread_mutex_t lock;
+ struct cds_list_head bodies;
+ struct cds_list_head freed;
+
+ struct acc alive;
+ struct acc reborn;
+} hpb_stats = {
+ .lock = PTHREAD_MUTEX_INITIALIZER,
+ .bodies = CDS_LIST_HEAD_INIT(hpb_stats.bodies),
+ .freed = CDS_LIST_HEAD_INIT(hpb_stats.freed),
+ .alive = ACC_INIT(hpb_stats.alive),
+ .reborn = ACC_INIT(hpb_stats.reborn)
+};
+
/* allocated via real_malloc/real_free */
struct src_loc {
pthread_mutex_t *mtx;
@@ -237,6 +274,9 @@ struct alloc_hdr {
struct src_loc *loc;
} live;
struct rcu_head dead;
+ struct {
+ size_t at; /* rb_gc_count() */
+ } hpb_freed;
} as;
void *real; /* what to call real_free on */
size_t size;
@@ -276,6 +316,52 @@ static int loc_eq(struct cds_lfht_node *node, const void *key)
memcmp(k->k, existing->k, loc_size(k)) == 0);
}
+/* note: not atomic */
+static void
+acc_add(struct acc *acc, size_t val)
+{
+ double delta = val - acc->mean;
+ size_t nr = ++acc->nr;
+
+ /* 32-bit overflow, ignore accuracy, just don't divide-by-zero */
+ if (nr)
+ acc->mean += delta / nr;
+
+ acc->m2 += delta * (val - acc->mean);
+ if (val < acc->min)
+ acc->min = val;
+ if (val > acc->max)
+ acc->max = val;
+}
+
+static VALUE
+acc_max(const struct acc *acc)
+{
+ return acc->max ? SIZET2NUM(acc->max) : DBL2NUM(HUGE_VAL);
+}
+
+static VALUE
+acc_min(const struct acc *acc)
+{
+ return acc->min == SIZE_MAX ? DBL2NUM(HUGE_VAL) : SIZET2NUM(acc->min);
+}
+
+static VALUE
+acc_mean(const struct acc *acc)
+{
+ return DBL2NUM(acc->nr ? acc->mean : HUGE_VAL);
+}
+
+static VALUE
+acc_stddev(const struct acc *acc)
+{
+ if (acc->nr > 1) {
+ double variance = acc->m2 / (acc->nr - 1);
+ DBL2NUM(sqrt(variance));
+ }
+ return INT2NUM(0);
+}
+
static struct src_loc *totals_add_rcu(struct src_loc *k)
{
struct cds_lfht_iter iter;
@@ -391,7 +477,7 @@ void free(void *p)
struct src_loc *l = h->as.live.loc;
if (!real_free) return; /* oh well, leak a little */
- if (l) {
+ if (l && l != IS_HEAP_PAGE_BODY) {
size_t age = generation - h->as.live.gen;
uatomic_add(&total_bytes_dec, h->size);
@@ -406,8 +492,20 @@ void free(void *p)
mutex_unlock(l->mtx);
call_rcu(&h->as.dead, free_hdr_rcu);
- }
- else {
+ } else if (l == IS_HEAP_PAGE_BODY) {
+ size_t gen = generation;
+ size_t age = gen - h->as.live.gen;
+
+ h->as.hpb_freed.at = gen;
+
+ mutex_lock(&hpb_stats.lock);
+ acc_add(&hpb_stats.alive, age);
+
+ /* hpb_stats.bodies => hpb_stats.freed */
+ cds_list_move(&h->anode, &hpb_stats.freed);
+
+ mutex_unlock(&hpb_stats.lock);
+ } else {
real_free(h->real);
}
}
@@ -434,7 +532,7 @@ static size_t size_align(size_t size, size_t alignment)
return ((size + (alignment - 1)) & ~(alignment - 1));
}
-static bool ptr_is_aligned(void *ptr, size_t alignment)
+static bool ptr_is_aligned(const void *ptr, size_t alignment)
{
return ((uintptr_t)ptr & (alignment - 1)) == 0;
}
@@ -473,18 +571,68 @@ internal_memalign(void **pp, size_t alignment, size_t size, uintptr_t caller)
__builtin_add_overflow(asize, sizeof(struct alloc_hdr), &asize))
return ENOMEM;
- /* assert(asize == (alignment + size + sizeof(struct alloc_hdr))); */
- l = track_memalign ? update_stats_rcu_lock(size, caller) : 0;
- real = real_malloc(asize);
- if (real) {
- void *p = hdr2ptr(real);
- if (!ptr_is_aligned(p, alignment))
- p = ptr_align(p, alignment);
- h = ptr2hdr(p);
- alloc_insert_rcu(l, h, size, real);
+
+ if (alignment == HEAP_PAGE_ALIGN && size == HEAP_PAGE_SIZE) {
+ if (has_ec_p()) generation = rb_gc_count();
+ l = IS_HEAP_PAGE_BODY;
+ } else if (track_memalign) {
+ l = update_stats_rcu_lock(size, caller);
+ } else {
+ l = 0;
+ }
+
+ if (l == IS_HEAP_PAGE_BODY) {
+ void *p;
+ size_t gen = generation;
+
+ mutex_lock(&hpb_stats.lock);
+
+ /* reuse existing entry */
+ if (!cds_list_empty(&hpb_stats.freed)) {
+ size_t deathspan;
+
+ h = cds_list_first_entry(&hpb_stats.freed,
+ struct alloc_hdr, anode);
+ /* hpb_stats.freed => hpb_stats.bodies */
+ cds_list_move(&h->anode, &hpb_stats.bodies);
+ assert(h->size == size);
+ assert(h->real);
+ real = h->real;
+ p = hdr2ptr(h);
+ assert(ptr_is_aligned(p, alignment));
+
+ deathspan = gen - h->as.hpb_freed.at;
+ acc_add(&hpb_stats.reborn, deathspan);
+ }
+ else {
+ real = real_malloc(asize);
+ if (!real) return ENOMEM;
+
+ p = hdr2ptr(real);
+ if (!ptr_is_aligned(p, alignment))
+ p = ptr_align(p, alignment);
+ h = ptr2hdr(p);
+ h->size = size;
+ h->real = real;
+ cds_list_add(&h->anode, &hpb_stats.bodies);
+ }
+ mutex_unlock(&hpb_stats.lock);
+ h->as.live.loc = l;
+ h->as.live.gen = gen;
*pp = p;
}
- update_stats_rcu_unlock(l);
+ else {
+ real = real_malloc(asize);
+ if (real) {
+ void *p = hdr2ptr(real);
+ if (!ptr_is_aligned(p, alignment))
+ p = ptr_align(p, alignment);
+ h = ptr2hdr(p);
+ alloc_insert_rcu(l, h, size, real);
+ update_stats_rcu_unlock(l);
+ *pp = p;
+ }
+ }
return real ? 0 : ENOMEM;
}
@@ -1052,6 +1200,75 @@ static VALUE total_dec(VALUE mod)
return SIZET2NUM(total_bytes_dec);
}
+static VALUE hpb_each_yield(VALUE ignore)
+{
+ struct alloc_hdr *h, *next;
+
+ cds_list_for_each_entry_safe(h, next, &hpb_stats.bodies, anode) {
+ VALUE v[2]; /* [ generation, address ] */
+ void *addr = hdr2ptr(h);
+ assert(ptr_is_aligned(addr, HEAP_PAGE_ALIGN));
+ v[0] = sizeof(void *) == sizeof(long) ?
+ LONG2NUM((long)addr) :
+ LL2NUM((LONG_LONG)addr);
+ v[1] = SIZET2NUM(h->as.live.gen);
+ rb_yield_values2(2, v);
+ }
+ return Qnil;
+}
+
+/*
+ * call-seq:
+ *
+ * Mwrap::HeapPageBody.each { |gen, addr| } -> Integer
+ *
+ * Yields the generation (GC.count) the heap page body was created
+ * and address of the heap page body as an Integer. Returns the
+ * number of allocated pages as an Integer. This return value should
+ * match the result of GC.stat(:heap_allocated_pages)
+ */
+static VALUE hpb_each(VALUE mod)
+{
+ ++locating;
+ return rb_ensure(hpb_each_yield, Qfalse, reset_locating, 0);
+}
+
+/*
+ * call-seq:
+ *
+ * Mwrap::HeapPageBody.stat -> Hash
+ * Mwrap::HeapPageBody.stat(hash) -> hash
+ *
+ * The maximum lifespan of a heap page body in the Ruby VM.
+ * This may be Infinity if no heap page bodies were ever freed.
+ */
+static VALUE hpb_stat(int argc, VALUE *argv, VALUE hpb)
+{
+ VALUE h;
+
+ rb_scan_args(argc, argv, "01", &h);
+ if (NIL_P(h))
+ h = rb_hash_new();
+ else if (!RB_TYPE_P(h, T_HASH))
+ rb_raise(rb_eTypeError, "not a hash %+"PRIsVALUE, h);
+
+ ++locating;
+#define S(x) ID2SYM(rb_intern(#x))
+ rb_hash_aset(h, S(lifespan_max), acc_max(&hpb_stats.alive));
+ rb_hash_aset(h, S(lifespan_min), acc_min(&hpb_stats.alive));
+ rb_hash_aset(h, S(lifespan_mean), acc_mean(&hpb_stats.alive));
+ rb_hash_aset(h, S(lifespan_stddev), acc_stddev(&hpb_stats.alive));
+ rb_hash_aset(h, S(deathspan_max), acc_max(&hpb_stats.reborn));
+ rb_hash_aset(h, S(deathspan_min), acc_min(&hpb_stats.reborn));
+ rb_hash_aset(h, S(deathspan_mean), acc_mean(&hpb_stats.reborn));
+ rb_hash_aset(h, S(deathspan_stddev), acc_stddev(&hpb_stats.reborn));
+ rb_hash_aset(h, S(resurrects), SIZET2NUM(hpb_stats.reborn.nr));
+#undef S
+ --locating;
+
+ return h;
+}
+
/*
* Document-module: Mwrap
*
@@ -1083,7 +1300,7 @@ static VALUE total_dec(VALUE mod)
*/
void Init_mwrap(void)
{
- VALUE mod;
+ VALUE mod, hpb;
++locating;
mod = rb_define_module("Mwrap");
@@ -1105,6 +1322,8 @@ void Init_mwrap(void)
rb_define_singleton_method(mod, "quiet", mwrap_quiet, 0);
rb_define_singleton_method(mod, "total_bytes_allocated", total_inc, 0);
rb_define_singleton_method(mod, "total_bytes_freed", total_dec, 0);
+
+
rb_define_method(cSrcLoc, "each", src_loc_each, 0);
rb_define_method(cSrcLoc, "frees", src_loc_frees, 0);
rb_define_method(cSrcLoc, "allocations", src_loc_allocations, 0);
@@ -1112,6 +1331,18 @@ void Init_mwrap(void)
rb_define_method(cSrcLoc, "mean_lifespan", src_loc_mean_lifespan, 0);
rb_define_method(cSrcLoc, "max_lifespan", src_loc_max_lifespan, 0);
rb_define_method(cSrcLoc, "name", src_loc_name, 0);
+
+ /*
+ * Information about "struct heap_page_body" allocations from
+ * Ruby gc.c. This can be useful for tracking fragmentation
+ * from posix_memalign(3) use in mainline Ruby:
+ *
+ * https://sourceware.org/bugzilla/show_bug.cgi?id=14581
+ */
+ hpb = rb_define_class_under(mod, "HeapPageBody", rb_cObject);
+ rb_define_singleton_method(hpb, "stat", hpb_stat, -1);
+ rb_define_singleton_method(hpb, "each", hpb_each, 0);
+
--locating;
}
diff --git a/lib/mwrap_rack.rb b/lib/mwrap_rack.rb
index a750f32..e45b26d 100644
--- a/lib/mwrap_rack.rb
+++ b/lib/mwrap_rack.rb
@@ -92,6 +92,53 @@ class MwrapRack
end
end
+ class HeapPages # :nodoc:
+ include HtmlResponse
+ HEADER = '<tr><th>address</th><th>generation</th></tr>'
+
+ def hpb_rows
+ Mwrap::HeapPageBody.stat(stat = Thread.current[:mwrap_hpb_stat] ||= {})
+ %i(lifespan_max lifespan_min lifespan_mean lifespan_stddev
+ deathspan_max deathspan_min deathspan_mean deathspan_stddev
+ resurrects
+ ).map! do |k|
+ "<tr><td>#{k}</td><td>#{stat[k]}</td></tr>\n"
+ end.join
+ end
+
+ def gc_stat_rows
+ GC.stat(stat = Thread.current[:mwrap_gc_stat] ||= {})
+ %i(count heap_allocated_pages heap_eden_pages heap_tomb_pages
+ total_allocated_pages total_freed_pages).map do |k|
+ "<tr><td>GC.stat(:#{k})</td><td>#{stat[k]}</td></tr>\n"
+ end.join
+ end
+
+ GC_STAT_URL = 'https://docs.ruby-lang.org/en/trunk/GC.html#method-c-stat'
+ GC_STAT_HELP = <<~""
+ <p>Non-Infinity lifespans can indicate fragmentation.
+ <p>See <a
+ href="#{GC_STAT_URL}">#{GC_STAT_URL}</a> for info on GC.stat values.
+
+ def each
+ Mwrap.quiet do
+ yield("<html><head><title>heap pages</title></head>" \
+ "<body><h1>heap pages</h1>" \
+ "<table><tr><th>stat</th><th>value</th></tr>\n" \
+ "#{hpb_rows}" \
+ "#{gc_stat_rows}" \
+ "</table>\n" \
+ "#{GC_STAT_HELP}" \
+ "<table>#{HEADER}")
+ Mwrap::HeapPageBody.each do |addr, generation|
+ addr = -sprintf('0x%x', addr)
+ yield(-"<tr><td>#{addr}</td><td>#{generation}</td></tr>\n")
+ end
+ yield "</table></body></html>\n"
+ end
+ end
+ end
+
def r404 # :nodoc:
[404,{'Content-Type'=>'text/plain'},["Not found\n"]]
end
@@ -107,12 +154,16 @@ class MwrapRack
loc = -CGI.unescape($1)
loc = Mwrap[loc] or return r404
EachAt.new(loc).response
+ when '/heap_pages'
+ HeapPages.new.response
when '/'
n = 2000
u = 'https://80x24.org/mwrap/README.html'
b = -('<html><head><title>Mwrap demo</title></head>' \
"<body><p><a href=\"each/#{n}\">allocations >#{n} bytes</a>" \
- "<p><a href=\"#{u}\">#{u}</a></body></html>\n")
+ "<p><a href=\"#{u}\">#{u}</a>" \
+ "<p><a href=\"heap_pages\">heap pages</a>" \
+ "</body></html>\n")
[ 200, {'Content-Type'=>'text/html','Content-Length'=>-b.size.to_s},[b]]
else
r404
diff --git a/test/test_mwrap.rb b/test/test_mwrap.rb
index d112b4e..6c66460 100644
--- a/test/test_mwrap.rb
+++ b/test/test_mwrap.rb
@@ -283,4 +283,33 @@ class TestMwrap < Test::Unit::TestCase
abort 'freed more than allocated'
end;
end
+
+ def test_heap_page_body
+ assert_separately(+"#{<<~"begin;"}\n#{<<~'end;'}")
+ begin;
+ require 'mwrap'
+ require 'rubygems' # use up some memory
+ ap = GC.stat(:heap_allocated_pages)
+ h = {}
+ nr = 0
+ Mwrap::HeapPageBody.each do |addr, gen|
+ nr += 1
+ gen <= GC.count && gen >= 0 or abort "bad generation: #{gen}"
+ (0 == (addr & 16383)) or abort "addr not aligned: #{'%x' % addr}"
+ end
+ nr == ap or abort 'HeapPageBody.each missed page'
+ 5.times { (1..20000).to_a.map(&:to_s) }
+ 3.times { GC.start }
+ Mwrap::HeapPageBody.stat(h)
+ Integer === h[:lifespan_max] or abort 'lifespan_max not recorded'
+ Integer === h[:lifespan_min] or abort 'lifespan_min not recorded'
+ Float === h[:lifespan_mean] or abort 'lifespan_mean not recorded'
+ 3.times { GC.start }
+ 5.times { (1..20000).to_a.map(&:to_s) }
+ Mwrap::HeapPageBody.stat(h)
+ h[:deathspan_min] <= h[:deathspan_max] or
+ abort 'wrong min/max deathtime'
+ Float === h[:deathspan_mean] or abort 'deathspan_mean not recorded'
+ end;
+ end
end
--
EW
^ permalink raw reply related [relevance 4%]
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-- pct% links below jump to the message on this page, permalinks otherwise --
2018-08-10 6:49 4% [PATCH] keep stats for memalign-ed heap_page_body in Ruby Eric Wong
2018-08-11 4:31 7% [ANN] mwrap 2.1.0 mwrap - LD_PRELOAD malloc wrapper for Ruby Eric Wong
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