◀Table of Contents
Development Tools for Ruby
TruffleRuby ships with tools automatically provided by GraalVM. Run --help:tools to see a full list of options.
The following program is used for illustration:
require 'chunky_png'
a = ChunkyPNG::Image.from_file('a.png')
b = ChunkyPNG::Image.from_file('b.png')
c = a.compose(b, 0, 0)
c.save('c.png')
VisualVM
Install VisualVM from its website.
VisualVM is a GUI with many tools:
- monitoring such as CPU usage, heap size, time spent in GC, etc (tab: Monitor)
- capturing and exploring heap dumps (tab: Monitor)
- a list of threads and their status, and thread dumps (tab: Threads)
- CPU and memory sampling profilers at the Java level (tab: Sampler)
- a CPU sampling profiler at the Ruby level (tab: Polyglot Sampler)
There is more documentation about VisualVM on the GraalVM website.
Profiling
CPU Tracer
The CPU tracer records the number of times methods, blocks, or statements that are run, and prints a histogram.
Enable it with --cputracer:
-----------------------------------------------------------------------------------------------------------------------------------
Tracing Histogram. Counted a total of 41663 element executions.
Total Count: Number of times the element was executed and percentage of total executions.
Interpreted Count: Number of times the element was interpreted and percentage of total executions of this element.
Compiled Count: Number of times the compiled element was executed and percentage of total executions of this element.
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Name | Total Count | Interpreted Count | Compiled Count | Location
-----------------------------------------------------------------------------------------------------------------------------------
ChunkyPNG::Color#a | 6474 15.5% | 6474 100.0% | 0 0.0% | chunky_png/color.rb~296-298:12189-12237
block in ChunkyPNG::Canvas::PNGDecoding#decode_png_str_scanline_paeth | 5248 12.6% | 5248 100.0% | 0 0.0% | chunky_png/canvas/png_decoding.rb~476:25098-25131
ChunkyPNG::Color#int8_mult | 3619 8.7% | 3619 100.0% | 0 0.0% | chunky_png/color.rb~344-347:13821-13900
ChunkyPNG::Canvas#width | 3205 7.7% | 3205 100.0% | 0 0.0% | chunky_png/canvas.rb~50:1853-1874
block in ChunkyPNG::Canvas::PNGEncoding#encode_png_str_scanline_up | 3072 7.4% | 3072 100.0% | 0 0.0% | chunky_png/canvas/png_encoding.rb~404:20111-20145
ChunkyPNG::Canvas#get_pixel | 2048 4.9% | 2048 100.0% | 0 0.0% | chunky_png/canvas.rb~184-186:7144-7203
ChunkyPNG::Color#opaque? | 1872 4.5% | 1872 100.0% | 0 0.0% | chunky_png/color.rb~304-306:12410-12468
ChunkyPNG::Color#fully_transparent? | 1500 3.6% | 1500 100.0% | 0 0.0% | chunky_png/color.rb~327-329:13138-13207
block in ChunkyPNG::Canvas::PNGDecoding#decode_png_str_scanline_up | 1408 3.4% | 1408 100.0% | 0 0.0% | chunky_png/canvas/png_decoding.rb~453:24009-24042
block in ChunkyPNG::Canvas::PNGDecoding#decode_png_str_scanline_sub | 1280 3.1% | 1280 100.0% | 0 0.0% | chunky_png/canvas/png_decoding.rb~443:23517-23550
ChunkyPNG::Color#b | 1037 2.5% | 1037 100.0% | 0 0.0% | chunky_png/color.rb~288-290:11969-12024
ChunkyPNG::Color#r | 1036 2.5% | 1036 100.0% | 0 0.0% | chunky_png/color.rb~272-274:11534-11590
ChunkyPNG::Color#g | 1035 2.5% | 1035 100.0% | 0 0.0% | chunky_png/color.rb~280-282:11752-11808
ChunkyPNG::Color#compose_quick | 1024 2.5% | 1024 100.0% | 0 0.0% | chunky_png/color.rb~358-368:14300-14740
ChunkyPNG::Canvas#set_pixel | 1024 2.5% | 1024 100.0% | 0 0.0% | chunky_png/canvas.rb~149-151:5706-5780
block (2 levels) in ChunkyPNG::Canvas::Operations#compose! | 1024 2.5% | 1024 100.0% | 0 0.0% | chunky_png/canvas/operations.rb~58:2331-2367
block in ChunkyPNG::Palette#opaque? | 848 2.0% | 848 100.0% | 0 0.0% | chunky_png/palette.rb~89:3319-3361
SortedSet#add | 848 2.0% | 848 100.0% | 0 0.0% | lib/mri/set.rb~741-745:1000-1169
ChunkyPNG::Color#rgba | 518 1.2% | 518 100.0% | 0 0.0% | chunky_png/color.rb~100-102:3905-3973
block in ChunkyPNG::Canvas::PNGDecoding#decode_png_str_scanline_average | 256 0.6% | 256 100.0% | 0 0.0% | chunky_png/canvas/png_decoding.rb~464:24513-24546
rb_str_new | 199 0.5% | 199 100.0% | 0 0.0% | src/main/c/cext/ruby.c~837:23634-23684
is_managed_rstring_ptr | 193 0.5% | 193 100.0% | 0 0.0% | src/main/c/cext/ruby.c~832:23499-23538
is_rstring_ptr | 193 0.5% | 193 100.0% | 0 0.0% | src/main/c/cext/ruby.c~828:23430-23461
strlen | 190 0.5% | 190 100.0% | 0 0.0% | string.c~56:0
rb_str_new_cstr | 190 0.5% | 190 100.0% | 0 0.0% | src/main/c/cext/ruby.c~858:24268-24310
RB_NIL_P | 138 0.3% | 138 100.0% | 0 0.0% | src/main/c/cext/ruby.c~413:11068-11094
Note how the C function strlen and the C preprocessor macro RB_NIL_P show up, being called by the zlib C extension.
CPU Sampler
The CPU tracer records the cumulative time spent executing methods, blocks, or statements, and prints a histogram. Enable it with --cpusampler:
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Sampling Histogram. Recorded 3895 samples with period 1ms.
Self Time: Time spent on the top of the stack.
Total Time: Time spent somewhere on the stack.
Opt %: Percent of time spent in compiled and therefore non-interpreted code.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Thread: Thread[main,5,main]
Name | Total Time | Opt % || Self Time | Opt % | Location
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------
<main> | 3635ms 93.3% | 0.0% || 1086ms 27.9% | 0.0% | test.rb~1-6:0-140
<top (required)> | 1068ms 27.4% | 0.0% || 708ms 18.2% | 0.0% | chunky_png.rb~1-179:0-5528
block in ChunkyPNG::Canvas::PNGEncoding#encode_png_str_scanline_up | 643ms 16.5% | 0.0% || 643ms 16.5% | 0.0% | chunky_png/canvas/png_encoding.rb~404:20111-20145
__sulong_dispose_context | 260ms 6.7% | 0.0% || 257ms 6.6% | 0.0% | sulong_dispose_context.c~33:0
block in ChunkyPNG::Canvas::PNGDecoding#decode_png_str_scanline_paeth | 58ms 1.5% | 0.0% || 58ms 1.5% | 0.0% | chunky_png/canvas/png_decoding.rb~476:25098-25131
do_checksum | 77ms 2.0% | 0.0% || 47ms 1.2% | 0.0% | src/main/c/zlib/zlib.c~389:12721-12796
ChunkyPNG::Palette#initialize | 52ms 1.3% | 0.0% || 41ms 1.1% | 0.0% | chunky_png/palette.rb~21-24:954-1074
block in Gem::Specification.load | 39ms 1.0% | 0.0% || 39ms 1.0% | 0.0% | bigdecimal-1.4.1.gemspec~5:126-154
rb_define_method | 50ms 1.3% | 0.0% || 36ms 0.9% | 0.0% | src/main/c/cext/ruby.c~2185:61849-61941
rb_tr_init | 44ms 1.1% | 0.0% || 34ms 0.9% | 0.0% | src/main/c/cext/ruby.c~93:2351-2384
<top (required)> | 42ms 1.1% | 0.0% || 33ms 0.8% | 0.0% | chunky_png/canvas.rb~1-372:0-13593
__sulong_byte_array_to_native | 30ms 0.8% | 0.0% || 30ms 0.8% | 0.0% | crt0.c~59:0
rb_str_new | 33ms 0.8% | 0.0% || 29ms 0.7% | 0.0% | src/main/c/cext/ruby.c~837:23634-23684
__sulong_init_context | 68ms 1.7% | 0.0% || 26ms 0.7% | 0.0% | crt0.c~80:0
Init_zlib | 145ms 3.7% | 0.0% || 24ms 0.6% | 0.0% | src/main/c/zlib/zlib.c~4465:112360-112374
rb_zlib_crc32 | 101ms 2.6% | 0.0% || 24ms 0.6% | 0.0% | src/main/c/zlib/zlib.c~473:14760-14808
rb_data_typed_object_wrap | 21ms 0.5% | 0.0% || 21ms 0.5% | 0.0% | src/main/c/cext/ruby.c~2834:79544-79639
rb_tr_load_library | 22ms 0.6% | 0.0% || 20ms 0.5% | 0.0% | src/main/c/cext/ruby.c~2906:81858-81897
ChunkyPNG::Canvas::PNGEncoding#encode_png_str_scanline_up | 662ms 17.0% | 0.0% || 19ms 0.5% | 0.0% | chunky_png/canvas/png_encoding.rb~403-409:20027-20347
rb_define_class_id_under | 18ms 0.5% | 0.0% || 18ms 0.5% | 0.0% | src/main/c/cext/ruby.c~2165:61106-61178
ChunkyPNG::Chunk.read | 137ms 3.5% | 0.0% || 17ms 0.4% | 0.0% | chunky_png/chunk.rb~18-26:783-1054
Datastream | 15ms 0.4% | 0.0% || 15ms 0.4% | 0.0% | chunky_png/datastream.rb~11:364-381
ChunkyPNG::Color#compose_quick | 37ms 0.9% | 0.0% || 14ms 0.4% | 0.0% | chunky_png/color.rb~358-368:14300-14740
rb_deflate_s_deflate | 27ms 0.7% | 0.0% || 13ms 0.3% | 0.0% | src/main/c/zlib/zlib.c~1622:44042-44097
ChunkyPNG::Canvas::PNGDecoding#decode_png_str_scanline_paeth | 71ms 1.8% | 0.0% || 13ms 0.3% | 0.0% | chunky_png/canvas/png_decoding.rb~475-488:25010-25650
ChunkyPNG::Palette.from_canvas | 64ms 1.6% | 0.0% || 12ms 0.3% | 0.0% | chunky_png/palette.rb~63-68:2377-2629
__sulong_byte_arrays_to_native | 42ms 1.1% | 0.0% || 12ms 0.3% | 0.0% | crt0.c~69:0
ChunkyPNG::Chunk::ImageData.combine_chunks | 167ms 4.3% | 0.0% || 12ms 0.3% | 0.0% | chunky_png/chunk.rb~247-253:9766-9980
rb_inflate_initialize | 19ms 0.5% | 0.0% || 12ms 0.3% | 0.0% | src/main/c/zlib/zlib.c~1887:51522-51576
strlen | 12ms 0.3% | 0.0% || 12ms 0.3% | 0.0% | string.c~56:0
zstream_run | 76ms 2.0% | 0.0% || 12ms 0.3% | 0.0% | src/main/c/zlib/zlib.c~1024:27867-27929
By default you see this histogram, but you can also see a call tree with --cpusampler.Output=calltree.
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Sampling CallTree. Recorded 3102 samples with period 1ms.
Self Time: Time spent on the top of the stack.
Total Time: Time spent somewhere on the stack.
Opt %: Percent of time spent in compiled and therefore non-interpreted code.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Thread: Thread[main,5,main]
Name | Total Time | Opt % || Self Time | Opt % | Location
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
ChunkyPNG::Canvas::PNGEncoding#save | 582ms 18.8% | 0.0% || 5ms 0.2% | 0.0% | chunky_png/canvas/png_encoding.rb~42-44:1754-1871
block in ChunkyPNG::Canvas::PNGEncoding#save | 577ms 18.6% | 0.0% || 0ms 0.0% | 0.0% | chunky_png/canvas/png_encoding.rb~43:1797-1861
ChunkyPNG::Canvas::PNGEncoding#write | 577ms 18.6% | 0.0% || 0ms 0.0% | 0.0% | chunky_png/canvas/png_encoding.rb~34-36:1430-1521
ChunkyPNG::Image#to_datastream | 571ms 18.4% | 0.0% || 0ms 0.0% | 0.0% | chunky_png/image.rb~61-65:2314-2447
ChunkyPNG::Canvas::PNGEncoding#to_datastream | 569ms 18.3% | 0.0% || 1ms 0.0% | 0.0% | chunky_png/canvas/png_encoding.rb~74-89:3715-4561
ChunkyPNG::Canvas::PNGEncoding#encode_png_pixelstream | 489ms 15.8% | 0.0% || 0ms 0.0% | 0.0% | chunky_png/canvas/png_encoding.rb~153-165:7702-8570
ChunkyPNG::Canvas::PNGEncoding#encode_png_image_without_interlacing | 489ms 15.8% | 0.0% || 0ms 0.0% | 0.0% | chunky_png/canvas/png_encoding.rb~172-176:8925-9195
ChunkyPNG::Canvas::PNGEncoding#encode_png_image_pass_to_stream | 489ms 15.8% | 0.0% || 3ms 0.1% | 0.0% | chunky_png/canvas/png_encoding.rb~203-231:10502-11685
block in ChunkyPNG::Canvas::PNGEncoding#encode_png_image_pass_to_stream | 481ms 15.5% | 0.0% || 0ms 0.0% | 0.0% | chunky_png/canvas/png_encoding.rb~225:11418-11456
ChunkyPNG::Canvas::PNGEncoding#encode_png_str_scanline_up | 481ms 15.5% | 0.0% || 11ms 0.4% | 0.0% | chunky_png/canvas/png_encoding.rb~403-409:20027-20347
block in ChunkyPNG::Canvas::PNGEncoding#encode_png_str_scanline_up | 470ms 15.2% | 0.0% || 470ms 15.2% | 0.0% | chunky_png/canvas/png_encoding.rb~404:20111-20145
block in ChunkyPNG::Canvas::PNGEncoding#encode_png_image_pass_to_stream | 5ms 0.2% | 0.0% || 1ms 0.0% | 0.0% | chunky_png/canvas/png_encoding.rb~219:11252-11284
ChunkyPNG::Canvas::PNGEncoding#encode_png_pixels_to_scanline_truecolor_8bit | 4ms 0.1% | 0.0% || 4ms 0.1% | 0.0% | chunky_png/canvas/png_encoding.rb~236-238:11896-12009
ChunkyPNG::Canvas::PNGEncoding#determine_png_encoding | 60ms 1.9% | 0.0% || 2ms 0.1% | 0.0% | chunky_png/canvas/png_encoding.rb~102-145:5085-7303
ChunkyPNG::Canvas#palette | 51ms 1.6% | 0.0% || 0ms 0.0% | 0.0% | chunky_png/canvas.rb~268-270:10089-10154
ChunkyPNG::Palette.from_canvas | 51ms 1.6% | 0.0% || 9ms 0.3% | 0.0% | chunky_png/palette.rb~63-68:2377-2629
ChunkyPNG::Palette#initialize | 42ms 1.4% | 0.0% || 30ms 1.0% | 0.0% | chunky_png/palette.rb~21-24:954-1074
SortedSet#initialize | 12ms 0.4% | 0.0% || 0ms 0.0% | 0.0% | lib/mri/set.rb~726-729:725-819
SortedSet#merge | 12ms 0.4% | 0.0% || 6ms 0.2% | 0.0% | lib/mri/set.rb~770-773:1759-1847
SortedSet#add | 6ms 0.2% | 0.0% || 6ms 0.2% | 0.0% | lib/mri/set.rb~741-745:1000-1169
ChunkyPNG::Palette#best_color_settings | 7ms 0.2% | 0.0% || 0ms 0.0% | 0.0% | chunky_png/palette.rb~195-211:7150-7613
ChunkyPNG::Palette#opaque? | 3ms 0.1% | 0.0% || 0ms 0.0% | 0.0% | chunky_png/palette.rb~88-90:3303-3369
SortedSet#each | 3ms 0.1% | 0.0% || 2ms 0.1% | 0.0% | lib/mri/set.rb~775-779:1850-2004
block in ChunkyPNG::Palette#opaque? | 1ms 0.0% | 0.0% || 0ms 0.0% | 0.0% | chunky_png/palette.rb~89:3319-3361
ChunkyPNG::Color#opaque? | 1ms 0.0% | 0.0% || 0ms 0.0% | 0.0% | chunky_png/color.rb~304-306:12410-12468
ChunkyPNG::Color#a | 1ms 0.0% | 0.0% || 1ms 0.0% | 0.0% | chunky_png/color.rb~296-298:12189-12237
ChunkyPNG::Palette#black_and_white? | 3ms 0.1% | 0.0% || 1ms 0.0% | 0.0% | chunky_png/palette.rb~104-106:3841-3940
SortedSet#each | 2ms 0.1% | 0.0% || 1ms 0.0% | 0.0% | lib/mri/set.rb~775-779:1850-2004
SortedSet#to_a | 1ms 0.0% | 0.0% || 1ms 0.0% | 0.0% | lib/mri/set.rb~781-784:2007-2116
ChunkyPNG::Palette#grayscale? | 1ms 0.0% | 0.0% || 0ms 0.0% | 0.0% | chunky_png/palette.rb~96-98:3570-3642
SortedSet#each | 1ms 0.0% | 0.0% || 1ms 0.0% | 0.0% | lib/mri/set.rb~775-779:1850-2004
ChunkyPNG::Chunk::ImageData.split_in_chunks | 19ms 0.6% | 0.0% || 7ms 0.2% | 0.0% | chunky_png/chunk.rb~255-259:9983-10267
rb_deflate_s_deflate | 12ms 0.4% | 0.0% || 4ms 0.1% | 0.0% | src/main/c/zlib/zlib.c~1622:44042-44097
rb_ensure | 5ms 0.2% | 0.0% || 1ms 0.0% | 0.0% | src/main/c/cext/ruby.c~2107:59266-59360
deflate_run | 4ms 0.1% | 0.0% || 0ms 0.0% | 0.0% | src/main/c/zlib/zlib.c~1589:43218-43240
zstream_run | 4ms 0.1% | 0.0% || 0ms 0.0% | 0.0% | src/main/c/zlib/zlib.c~1024:27867-27929
zstream_append_input | 1ms 0.0% | 0.0% || 0ms 0.0% | 0.0% | src/main/c/zlib/zlib.c~827:23738-23804
rb_str_buf_cat | 1ms 0.0% | 0.0% || 0ms 0.0% | 0.0% | src/main/c/cext/ruby.c~981:27520-27591
rb_str_cat | 1ms 0.0% | 0.0% || 0ms 0.0% | 0.0% | src/main/c/cext/ruby.c~882:24901-24968
rb_enc_str_new | 1ms 0.0% | 0.0% || 0ms 0.0% | 0.0% | src/main/c/cext/ruby.c~1301:37035-37101
Coverage
The coverage tool reports coverage by statement, line, and root.
Root means the root of a function, i.e., how many methods and blocks were covered.
Enable it with --coverage:
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Code coverage histogram.
Shows what percent of each element was covered during execution
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Path | Statements | Lines | Roots
-------------------------------------------------------------------------------------------------------------------------------------
chunky_png-1.3.11/lib/chunky_png.rb | 100.00% | 100.00% | 100.00%
chunky_png-1.3.11/lib/chunky_png/canvas.rb | 58.40% | 69.41% | 35.90%
chunky_png-1.3.11/lib/chunky_png/canvas/adam7_interlacing.rb | 28.57% | 50.00% | 28.57%
chunky_png-1.3.11/lib/chunky_png/canvas/data_url_exporting.rb | 80.00% | 83.33% | 80.00%
chunky_png-1.3.11/lib/chunky_png/canvas/data_url_importing.rb | 57.14% | 70.00% | 80.00%
chunky_png-1.3.11/lib/chunky_png/canvas/drawing.rb | 8.28% | 44.02% | 13.33%
chunky_png-1.3.11/lib/chunky_png/canvas/masking.rb | 28.57% | 51.72% | 44.44%
chunky_png-1.3.11/lib/chunky_png/canvas/operations.rb | 42.42% | 65.07% | 21.95%
chunky_png-1.3.11/lib/chunky_png/canvas/png_decoding.rb | 52.84% | 68.27% | 26.98%
chunky_png-1.3.11/lib/chunky_png/canvas/png_encoding.rb | 44.44% | 62.07% | 40.43%
chunky_png-1.3.11/lib/chunky_png/canvas/resampling.rb | 17.46% | 48.51% | 25.00%
chunky_png-1.3.11/lib/chunky_png/canvas/stream_exporting.rb | 61.54% | 72.22% | 44.44%
chunky_png-1.3.11/lib/chunky_png/canvas/stream_importing.rb | 31.82% | 45.83% | 40.00%
chunky_png-1.3.11/lib/chunky_png/chunk.rb | 82.84% | 86.32% | 68.42%
chunky_png-1.3.11/lib/chunky_png/color.rb | 41.82% | 59.00% | 33.93%
chunky_png-1.3.11/lib/chunky_png/compatibility.rb | 75.00% | 66.67% | 75.00%
chunky_png-1.3.11/lib/chunky_png/datastream.rb | 83.56% | 87.50% | 80.00%
chunky_png-1.3.11/lib/chunky_png/dimension.rb | 42.11% | 62.07% | 23.08%
chunky_png-1.3.11/lib/chunky_png/image.rb | 85.00% | 90.32% | 90.00%
chunky_png-1.3.11/lib/chunky_png/palette.rb | 41.18% | 63.46% | 42.31%
chunky_png-1.3.11/lib/chunky_png/point.rb | 42.86% | 62.96% | 25.00%
chunky_png-1.3.11/lib/chunky_png/vector.rb | 40.98% | 63.10% | 10.34%
chunky_png-1.3.11/lib/chunky_png/version.rb | 100.00% | 100.00% | 100.00%
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Debugging
Debugging with VSCode
This is the best-supported debugger for TruffleRuby, see this documentation.
Chrome Inspector
GraalVM lets you debug Ruby programs, and any other language supported by GraalVM, using the Chrome DevTools Protocol to attach to debuggers such as Chrome Developer Tools.
Run with --inspect, open the given URL in Chrome, drag your file system into the sources list, and then set a breakpoint and resume execution.
Having the debugger attached and simple breakpoints set should not reduce performance.
NetBeans
You can also debug GraalVM languages using NetBeans.
Run with --jvm --vm.agentlib:jdwp=transport=dt_socket,server=y,address=8000,suspend=y and attach to the process as if you were debugging a Java program.
Then click Toggle pause in GraalVM script (the pause icon with a G superimposed) and break, and you will break into the Ruby code.
You will see Ruby stack frames and local variables rather than Java stack frames and local variables.
