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Bug #12999
closedthere still exist race conditions in require
Description
TestRequire#test_require_with_loaded_features_pop fails by increasing the number of threads,
so it seems that there still exist race conditions in require.
lexington:ruby$ cat t/require_test.rb
require "tempfile"
Tempfile.create(%w'bug-7530- .rb') {|script|
script.close
PATH = script.path
THREADS = 10
ITERATIONS_PER_THREAD = 1000
THREADS.times.map {
Thread.new do
ITERATIONS_PER_THREAD.times do
require PATH
$".delete_if {|p| Regexp.new(PATH) =~ p}
end
end
}.each(&:join)
p :ok
}
lexington:ruby$ ./ruby t/require_test.rb
/home/shugo/local/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require': destroyed thread shield - 0x00557a99ff5a78 (ThreadError)
from /home/shugo/local/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from t/require_test.rb:12:in `block (4 levels) in <main>'
from t/require_test.rb:11:in `times'
from t/require_test.rb:11:in `block (3 levels) in <main>'
lexington:ruby$ ./ruby t/require_test.rb
/home/shugo/local/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require': Attempt to unlock a mutex which is locked by another thread (ThreadError)
from /home/shugo/local/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from t/require_test.rb:12:in `block (4 levels) in <main>'
from t/require_test.rb:11:in `times'
from t/require_test.rb:11:in `block (3 levels) in <main>'
Updated by shugo (Shugo Maeda) almost 8 years ago
- Related to Bug #7530: Concurrent loads fail with mutex errors added
Updated by shugo (Shugo Maeda) almost 8 years ago
In r56965, load_lock() was changed as follows:
switch (rb_thread_shield_wait((VALUE)data)) {
case Qfalse:
data = (st_data_t)ftptr;
st_insert(loading_tbl, data, (st_data_t)rb_thread_shield_new());
return 0;
case Qnil:
return 0;
}
However, if the thread shield is destroyed, it's not necessary to insert
a new entry to the loading table, is it?
With the following fix, ThreadError doesn't seem to occur:
diff --git a/load.c b/load.c
index 3cf9ce0..c37f8bc 100644
--- a/load.c
+++ b/load.c
@@ -745,9 +745,6 @@ load_lock(const char *ftptr)
}
switch (rb_thread_shield_wait((VALUE)data)) {
case Qfalse:
- data = (st_data_t)ftptr;
- st_insert(loading_tbl, data, (st_data_t)rb_thread_shield_new());
- return 0;
case Qnil:
return 0;
}
@@ -759,7 +756,10 @@ release_thread_shield(st_data_t *key, st_data_t *value, st_data_t done, int exis
{
VALUE thread_shield = (VALUE)*value;
if (!existing) return ST_STOP;
- if (done ? rb_thread_shield_destroy(thread_shield) : rb_thread_shield_release(thread_shield)) {
+ if (done) {
+ rb_thread_shield_destroy(thread_shield);
+ }
+ else if (rb_thread_shield_release(thread_shield)) {
/* still in-use */
return ST_CONTINUE;
}
Updated by shugo (Shugo Maeda) almost 8 years ago
- Status changed from Open to Closed
Applied in changeset r56985.
Don't insert an entry to loading_tbl if another thread succeed to load.
If rb_thread_shield_wait() returns Qfalse, the file has been successfully
loaded by another thread, so there is no need to insert a new entry into
loading_tbl. [ruby-core:78464] [Bug #12999]
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