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Bug #10902

closed

require("enumerator") scans LOAD_PATH 2x on every invocation

Added by tmm1 (Aman Karmani) over 7 years ago. Updated 7 months ago.

Status:
Closed
Priority:
Normal
Assignee:
-
Target version:
-
ruby -v:
ruby 2.1.5
[ruby-core:68290]
Tags:

Description

On every invocation of require "enumerator" (for example during boot when many gems require it), the VM will scan the load path twice: once for enumerator.rb and again for enumerator.so. Of course, no file is found because enumerator is now shipped within the VM by default.

$ ruby -e' p $LOADED_FEATURES[0] '
"enumerator.so"

$ ruby -e' p $LOAD_PATH.size '
8

$ strace -e trace=open ruby -e' 1.times{ require "enumerator" } ' 2>&1 | grep enumerator.rb | wc -l
8

$ strace -e trace=open ruby -e' 1.times{ require "enumerator" } ' 2>&1 | grep enumerator.so | wc -l
8

$ strace -e trace=open ruby -e' 10.times{ require "enumerator" } ' 2>&1 | grep enumerator.so | wc -l
80

$ strace -e trace=open ruby -e' 100.times{ require "enumerator" } ' 2>&1 | grep enumerator.so | wc -l
800

In enumerator.c, we call rb_provide("enumerator.so") which adds it to $LOADED_FEATURES. This means require "enumerator.so" can be optimized, but most libraries do not include the .so extension when requiring enumerator.

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