From: samuel@... Date: 2018-07-08T02:52:51+00:00 Subject: [ruby-core:87868] [Ruby trunk Bug#14900] Extra allocation in String#byteslice Issue #14900 has been updated by ioquatix (Samuel Williams). One thing I noticed if I freeze source string, the extra memory allocation goes away. ---------------------------------------- Bug #14900: Extra allocation in String#byteslice https://bugs.ruby-lang.org/issues/14900#change-72883 * Author: janko (Janko Marohni��) * Status: Open * Priority: Normal * Assignee: * Target version: * ruby -v: ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-darwin17] * Backport: 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: UNKNOWN ---------------------------------------- When executing `String#byteslice` with a range, I noticed that sometimes the original string is allocated again. When I run the following script: ~~~ ruby require "objspace" string = "a" * 100_000 GC.start GC.disable generation = GC.count ObjectSpace.trace_object_allocations do string.byteslice(50_000..-1) ObjectSpace.each_object(String) do |string| p string.bytesize if ObjectSpace.allocation_generation(string) == generation end end ~~~ it outputs ~~~ 50000 100000 6 5 ~~~ The one with 50000 bytes is the result of `String#byteslice`, but the one with 100000 bytes is the duplicated original string. I expected only the result of `String#byteslice` to be amongst new allocations. If instead of the last 50000 bytes I slice the *first* 50000 bytes, the extra duplication doesn't occur. ~~~ ruby # ... string.byteslice(0, 50_000) # ... ~~~ ~~~ 50000 5 ~~~ It's definitely ok if the implementation of `String#bytesize` allocates extra strings as part of the implementation, but it would be nice if they were deallocated before returning the result. EDIT: It seems that `String#slice` has the same issue. -- https://bugs.ruby-lang.org/ Unsubscribe: