Protect buffer operations in force_flush #1181
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force_flush is called from another thread, so accessing buffer should be guarded.
| @@ -291,7 +291,8 @@ def format_stream(tag, es) | |||
| #end | |||
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| def enqueue_buffer(force = false) | |||
| @buffer.keys.each {|key| | |||
| buf_keys = @buffer.synchronize { @buffer.keys } | |||
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Do @buffer.keys.dup in critical sections.
Your code iterates the object in @buffer itself, and doesn't protect anything in synchronize.
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@buffer.keys returns an array from internal @map hash keys.
What does '@buffer itself' mean?
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I tested on pry:
hash = {a: 1, b: 2, c: 3, d: 4}
=> {:a=>1, :b=>2, :c=>3, :d=>4}
t = Thread.new{ i = 0; hash.each{|k,v| p(k: v); sleep(5) if i == 1; i += 1 } }; sleep 1; hash[:e] = 5; p hash; sleep 3; p hash
{:k=>1}
{:k=>2}
RuntimeError: can't add a new key into hash during iteration
from (pry):12:in `__pry__'
{:k=>3}
{:k=>4}
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Ah, no, it's not what i want to test...
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I confirmed that you're right. Sorry to bother you.
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force_flush is called from another thread, so accessing buffer should be guarded.
See: #1129