Jemal
This gem provides interface to your MRI built with jemalloc. Of course you heard that Ruby 2.2.0 introduced jemalloc support.
Primary goal of this gem is to provide access to jemalloc statistics.
Currently jemalloc 3.6.0 is supported (certain Ruby gems can't yet be built with 4.0.0 due to stdbool.h conflict).
Note that there's another jemalloc-related gem on RubyGems. It doesn't provide interface to builtin jemalloc, but rather aims at injecting jemalloc in runtime with LD_PRELOAD.
Jemalloc installation
Ubuntu:
$ sudo apt-get install libjemalloc-dev
OS X:
$ brew install jemalloc
Note that if you want to use allocation profiling, you'll have to build
jemalloc from source (./configure --enable-prof). Both ubuntu and homebrew versions
are built without this option.
Ruby with jemalloc installation
Instructions are here.
Gem installation
Add this line to your application's Gemfile:
gem 'jemal'
And then execute:
$ bundle
Or install it yourself as:
$ gem install jemal
Usage
To be sure that your Ruby is jemalloc-powered, use Jemal.jemalloc_builtin?.
require 'jemal'
Jemal.jemalloc_builtin?
# => true
You can also check jemalloc version:
Jemal.version
# => "3.6.0-0-g46c0af68bd248b04df75e4f92d5fb804c3d75340"
Look at the flags jemalloc has been built with:
Jemal.build_configuration
# => {:debug=>false, :dss=>false, :fill=>true, :lazy_lock=>false, :mremap=>false, :munmap=>true,
# :prof=>false, :prof_libgcc=>false, :prof_libunwind=>false, :stats=>true, :tcache=>true,
# :tls=>false, :utrace=>false, :valgrind=>false, :xmalloc=>false}
Most of these options aren't very interesting, however be sure that Jemal.build_configuration[:stats] is true,
otherwise you won't be able to collect statistics.
Find out how many arenas are used by jemalloc:
Jemal.arenas_count
# => 16
Each arena is basically a separate allocator with its own memory. Multiple arenas provide more speed for heavily
multithreaded applications by allowing parallel threads to allocate memory simultaneously. This doesn't help MRI much, because its heap is still shared between all threads, so we can set MALLOC_CONF=narenas:1 in environment and have single arena.
Now to statistics:
Jemal.stats
# => {:allocated=>23587776, :active=>24416256, :metadata=>0, :resident=>0, :mapped=>29360128,
# :cactive=>37748736, :chunks=>{:current=>7, :total=>7, :high=>7},
# :arenas=>[ ... ]}
The returned hash is quite big, it contains joint statistics, as well as statistics for each arena. Read
jemalloc man page to be able to understand the figures (look for stats.*).
If you just want human-compatible stats in text form and STDERR is okay, you are also covered:
Jemal.stats_print
You'll get a jemalloc stats dump which looks like this:
___ Begin jemalloc statistics ___
Version: 3.6.0-0-g46c0af68bd248b04df75e4f92d5fb804c3d75340
Assertions disabled
Run-time option settings:
opt.abort: false
opt.lg_chunk: 22
opt.dss: "secondary"
opt.narenas: 16
opt.lg_dirty_mult: 3
opt.stats_print: false
opt.junk: false
opt.quarantine: 0
opt.redzone: false
opt.zero: false
opt.tcache: true
opt.lg_tcache_max: 15
CPUs: 4
Arenas: 16
Pointer size: 8
Quantum size: 16
Page size: 4096
Min active:dirty page ratio per arena: 8:1
Maximum thread-cached size class: 32768
Chunk size: 4194304 (2^22)
Allocated: 23781096, active: 25649152, mapped: 33554432
Current active ceiling: 37748736
chunks: nchunks highchunks curchunks
8 8 8
huge: nmalloc ndalloc allocated
0 0 0
arenas[0]:
assigned threads: 1
dss allocation precedence: disabled
dirty pages: 6262:52 active:dirty, 0 sweeps, 0 madvises, 0 purged
allocated nmalloc ndalloc nrequests
small: 17493736 317316 120581 678822
large: 6287360 432 56 1269
total: 23781096 317748 120637 680091
active: 25649152
mapped: 29360128
bins: bin size regs pgs allocated nmalloc ndalloc nrequests nfills nflushes newruns reruns curruns
0 8 501 1 87688 12194 1233 19899 246 25 23 32 23
1 16 252 1 200480 22361 9831 31078 279 113 81 162 52
2 32 126 1 1017088 36067 4283 81314 433 57 267 373 264
3 48 84 1 4174848 137466 50490 250234 1644 603 1140 3707 1072
4 64 63 1 331392 9969 4791 35396 335 98 115 273 104
5 80 50 1 691840 14013 5365 52709 353 122 197 682 182
6 96 84 2 269664 3921 1112 12273 87 47 45 55 40
7 112 72 2 433664 4481 609 7083 95 32 61 65 57
8 128 63 2 207488 2086 465 11407 84 35 32 42 28
9 160 51 2 2482880 49495 33977 106753 997 672 486 2895 313
10 192 63 3 205632 1643 572 3659 61 42 24 24 19
11 224 72 4 422688 2339 452 3222 62 35 31 17 28
12 256 63 4 152320 1049 454 1383 51 39 19 11 11
13 320 63 5 2549760 8587 619 11026 179 27 135 39 132
14 384 63 6 167040 749 314 1105 29 38 11 3 8
15 448 63 7 689472 2861 1322 5053 227 51 38 39 29
16 512 63 8 161280 551 236 552 35 35 11 5 6
17 640 51 8 693120 3729 2646 39605 119 74 42 224 25
18 768 47 9 328704 677 249 723 36 36 15 8 10
19 896 45 10 272384 560 256 660 36 35 14 9 7
20 1024 63 16 273408 475 208 464 31 37 7 4 5
21 1280 51 16 478720 686 312 1367 39 38 14 9 8
22 1536 42 16 259584 323 154 545 40 34 6 3 5
23 1792 38 17 236544 304 172 454 30 30 7 5 4
24 2048 65 33 182272 236 147 198 29 30 3 1 2
25 2560 52 33 245760 227 131 393 24 30 4 1 3
26 3072 43 33 181248 156 97 173 30 30 3 7 2
27 3584 39 35 96768 111 84 94 21 24 2 0 1
large: size pages nmalloc ndalloc nrequests curruns
4096 1 63 21 520 42
8192 2 89 17 465 72
12288 3 21 9 23 12
16384 4 243 3 244 240
20480 5 2 2 2 0
24576 6 2 2 2 0
28672 7 3 1 3 2
32768 8 6 1 7 5
[11]
81920 20 1 0 1 1
[2]
94208 23 1 0 1 1
[232]
1048576 256 1 0 1 1
[762]
--- End jemalloc statistics ---
Other methods of less interest:
Jemal. # Returns runtime jemalloc options
# => { :abort=>false, ... }
Jemal.sizes # Returns some constant sizes (page, bin, lrun)
# => { :page_size=>4096, ... }
Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/be9/jemal.
License
The gem is available as open source under the terms of the MIT License.