Implement a no-op gc #564
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Implement a no-op gc #564
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This is a new Garbage collector built using the new GC API introduced in https://bugs.ruby-lang.org/issues/20470 It's modelled on the Epsilon collector introduced in JDK 11. A No-Op collector that implements memory allocation but no memory reclamation. Memory will continue to be allocated until the process exhausts all available memory and is shut down by the OS's OOM killer. This GC has the lowest possible GC latency, at the expense of memory footprint and throughput. This is primarily useful for experimentation and testing, and provides a "second system" in order to continue testing the GC API. This collector uses the same heap/page/slot allocation strategy as Ruby's existing GC. This was done for a few reasons: - Memory throughput: Traditionally and Epsilon collector would malloc every allocation, this GC uses an already established Ruby allocation implementation to reduce the number of malloc/free calls during allocation, allowing allocation to be faster. - Familiarity: Developers of the Ruby GC are already familiar with how allocation works in Ruby, this GC should remain simple to work on. - Simplicity: Using the existing allocation strategy allowed us to develop this quickly, and avoid having to deal with alignment issues, or abstraction leakage issues over the API. The epsilon collection can be built as a shared library as follows: Mac: clang -I../src/include -I. -I../src -I.ext/include/arm64-darwin23 -Wall -undefined dynamic_lookup -g -O0 -dynamiclib -o gc/epsilon.dylib ../src/gc/epsilon.c Linux: gcc -O0 -g -I. -I../src/ -I../src/include -I./.ext/include/x86_64-linux/ -Wall -fPIC -shared -lc ../src/gc/epsilon.c -o gc/epsilon.so Ruby must be built with shared GC support, and the correct library directory set in the configure path. ./configure --with-shared-gc=$(pwd)/gc Then, the EpsilonGC can be loaded at runtime using the RUBY_GC_LIBRARY environment variable RUBY_GC_LIBRARY=epsilon.dylib ./ruby test.rb [Feature #20612]
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Try to implement a no-op GC for Ruby.
For the epsilon GC, compile with:
clang -I../include -I. -I../ -I.ext/include/arm64-darwin23 -I/opt/rubies/3.4.0-preview2/include/ruby-3.4.0+0/arm64-darwin23 -Wall -undefined dynamic_lookup -g -O0 -dynamiclib -o gc/librubygc.epsilon.dylib ../gc/epsilon.cThen configure your ruby to use the shared gc (in your build folder):
mkdir gc../configure cflags="-fno-omit-frame-pointer" --prefix=$(pwd)/target --disable-install-doc optflags=-O0 --with-opt-dir=$(brew --prefix gmp):$(brew --prefix jemalloc):$(brew --prefix llvm) --wi th-shared-gc=$(pwd)/gcThen run Ruby with the epsilon GC loaded:
RUBY_GC_LIBRARY=epsilon ./ruby -v test.rbThe version should indicate the GC being used:
ruby 3.4.0dev (2024-12-13T15:23:13Z epsilon-gc ca6664a3eb) +PRISM +GC[epsilon] [arm64-darwin24]