Ractor.make_shareable(obj) tries to make obj a shareable object
by changing the attribute of obj and traversable objects from obj
(mainly freeze them).
"copy: true" option is more conservative approach by make deep
copied object and make it sharable. It doesn't affect any existing
objects.
ObjectSpace._id2ref(id) can return any objects even if they are
unshareable, so this patch raises RangeError if it runs on multi-ractor
mode and the found object is unshareable.
Thread's interrupt set Ractor's wakeup_status as interrupted, but
the status remains next Ractor communication API. This patch makes
to ignore the previous interrupt state.
[Bug #17366]
Also this patch solves the Thread#kill and Ractor#take issues.
ractor_copy() used rb_ary_modify() to make sure this array is not
sharing anything, but it also checks frozen flag. So frozen arrays
raises an error. To solve this issue, this patch introduces new
function rb_ary_cancel_sharing() which makes sure the array does not
share another array and it doesn't check frozen flag.
[Bug #17343]
A test is quoted from https://github.com/ruby/ruby/pull/3817
close_incoming by antoher ractor means there is no other messages
will be sent to the ractor, so Ractor.receive will block forever,
and it should raise and stop.
close_outgoing by antoher ractor means, ... I don't have good idea
to use it. It can be a private method.
Ractor#close calls both, but it does not make sense to call
different purpose methods, so I remove it.
a method defined by define_method with normal Proc can not cross
ractors because the normal Proc is not shareable. However,
shareable Proc can be crossed between ractors, so the method with
shareable Proc should be called correctly.
Ractor.make_shareable() supports Proc object if
(1) a Proc only read outer local variables (no assignments)
(2) read outer local variables are shareable.
Read local variables are stored in a snapshot, so after making
shareable Proc, any assignments are not affeect like that:
```ruby
a = 1
pr = Ractor.make_shareable(Proc.new{p a})
pr.call #=> 1
a = 2
pr.call #=> 1 # `a = 2` doesn't affect
```
[Feature #17284]
Accessing a shareable object is prohibitted because it can cause
race condition, but if the shareable object is frozen, there is no
problem to access ivars.
Introduce new method Ractor.make_shareable(obj) which tries to make
obj shareable object. Protocol is here.
(1) If obj is shareable, it is shareable.
(2) If obj is not a shareable object and if obj can be shareable
object if it is frozen, then freeze obj. If obj has reachable
objects (rs), do rs.each{|o| Ractor.make_shareable(o)}
recursively (recursion is not Ruby-level, but C-level).
(3) Otherwise, raise Ractor::Error. Now T_DATA is not a shareable
object even if the object is frozen.
If the method finished without error, given obj is marked as
a sharable object.
To allow makng a shareable frozen T_DATA object, then set
`RUBY_TYPED_FROZEN_SHAREABLE` as type->flags. On default,
this flag is not set. It means user defined T_DATA objects are
not allowed to become shareable objects when it is frozen.
You can make any object shareable by setting FL_SHAREABLE flag,
so if you know that the T_DATA object is shareable (== thread-safe),
set this flag, at creation time for example. `Ractor` object is one
example, which is not a frozen, but a shareable object.
On Solaris, it seems to access ENV in ``, so skip it now.
```
stderr output is not empty
Exception `NameError' at bootstraptest.tmp.rb:7 - can not access non-sharable objects in constant Object::ENV by non-main Ractor.
#<Thread:0x0044cdf0 run> terminated with exception (report_on_exception is true):
bootstraptest.tmp.rb:7:in ``': can not access non-sharable objects in constant Object::ENV by non-main Ractor. (NameError)
Exception `Ractor::RemoteError' at <internal:ractor>:130 - thrown by remote Ractor.
<internal:ractor>:130:in `take': thrown by remote Ractor. (Ractor::RemoteError)
from bootstraptest.tmp.rb:55:in `<main>'
bootstraptest.tmp.rb:7:in ``': can not access non-sharable objects in constant Object::ENV by non-main Ractor. (NameError)
from bootstraptest.tmp.rb:7:in `ractor_local_globals'
from bootstraptest.tmp.rb:54:in `block in <main>'
```
Unshareable objects should not be touched from multiple ractors
so ObjectSpace.each_object should be restricted. On multi-ractor
mode, ObjectSpace.each_object only iterates shareable objects.
[Feature #17270]
generic_ivtbl is a process global table to maintain instance variables
for non T_OBJECT/T_CLASS/... objects. So we need to protect them
for multi-Ractor exection.
Hint: we can make them Ractor local for unshareable objects, but
now it is premature optimization.
enc_table which manages Encoding information. rb_encoding_list
also manages Encoding objects. Both are accessed/modified by ractors
simultaneously so that they should be synchronized.
For enc_table, this patch introduced GLOBAL_ENC_TABLE_ENTER/LEAVE/EVAL
to access this table with VM lock. To make shortcut, three new global
variables global_enc_ascii, global_enc_utf_8, global_enc_us_ascii are
also introduced.
For rb_encoding_list, we split it to rb_default_encoding_list (256 entries)
and rb_additional_encoding_list. rb_default_encoding_list is fixed sized Array
so we don't need to synchronized (and most of apps only needs it). To manage
257 or more encoding objects, they are stored into rb_additional_encoding_list.
To access rb_additional_encoding_list., VM lock is needed.
Koichi Sasada
Nobuyoshi Nakada
Takashi Kokubun
Marc-Andre Lafortune
Benoit Daloze