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author | akr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2017-12-01 10:48:29 +0000 |
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committer | akr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2017-12-01 10:48:29 +0000 |
commit | add309c49627b88cb20865dacee8dc17cd0d9525 (patch) | |
tree | e437cae92230676b1524f6d279ca7be2a86267d1 /vm_trace.c | |
parent | 58d572d6aab4b5c3b75b99bda0040e8846464c49 (diff) |
Replace Kernel#pp after PP class is defined.
Avoid a race condition which a context switch
occur after replacing Kernel#pp but before
defining PP class.
Following patch, inserting sleep, makes
this problem reproducible.
```
Index: lib/pp.rb
===================================================================
--- lib/pp.rb (revision 60960)
+++ lib/pp.rb (working copy)
@@ -26,6 +26,7 @@ module Kernel
end
undef __pp_backup__ if method_defined?(:__pp_backup__)
module_function :pp
+ sleep 1 # thread context switch
end
##
```
With the above patch, "uninitialized constant Kernel::PP" can
happen as as follows.
```
% ./ruby -w -Ilib -e '
t1 = Thread.new {
Thread.current.report_on_exception = true
pp :foo1
}
t2 = Thread.new {
Thread.current.report_on_exception = true
sleep 0.5
pp :foo2
}
t1.join rescue nil
t2.join rescue nil
'
#<Thread:0x000055dbf926eaa0@-e:6 run> terminated with exception:
Traceback (most recent call last):
3: from -e:9:in `block in <main>'
2: from /home/ruby/tst2/ruby/lib/pp.rb:22:in `pp'
1: from /home/ruby/tst2/ruby/lib/pp.rb:22:in `each'
/home/ruby/tst2/ruby/lib/pp.rb:23:in `block in pp': uninitialized constant Kernel::PP (NameError)
:foo1
```
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60961 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'vm_trace.c')
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