2009/10/19 Flier Lu <[email protected]>:
>
> Thanks for your suggestion
>
> After debugging the serialize/deserialize implementation, I found the
> root cause is that I entered a context before serialize the heap, so,
> the saved context was dumped to the snapshot file. When I load the
> snapshot, I can't enter a context, because Context::New will automatic
> initialize the v8 VM; it means, I missed a saved context in snapshot,
> and the verification will be failed.
>
> So, I just avoid to call the Context::enter and the load will be ok.
> Even so, I'm confused why the cctest code could do this?
I don't understand this either :-/.
>
> static void Serialize() {
> #ifdef DEBUG
> FLAG_debug_serialization = true;
> #endif
> StatsTable::SetCounterFunction(counter_function);
>
> v8::HandleScope scope;
> const int kExtensionCount = 1;
> const char* extension_list[kExtensionCount] = { "v8/gc" };
> v8::ExtensionConfiguration extensions(kExtensionCount,
> extension_list);
> Serializer::Enable();
> v8::Persistent<v8::Context> env = v8::Context::New(&extensions);
> env->Enter();
>
> Snapshot::WriteToFile(FLAG_testing_serialization_file);
> }
>
> static void Deserialize() {
> #ifdef DEBUG
> FLAG_debug_serialization = true;
> #endif
> CHECK(Snapshot::Initialize(FLAG_testing_serialization_file));
> }
>
> The other problem is that after I call the v8::internal::V8::Initialize
> (&deserializer) method, the stack around deserializer the will be
> destroyed. I'm not sure where is the root cause, so, just use a
> pointer of deserializer and leave it with memory leak :(
>
> On the other hand, I found the user registered extension will not be
> restore after load the snapshot. I could find the extension name and
> script int the snapshot file, but I can't find it in the
> RegisteredExtension::first_extension_ chain. Could you give me some
> hints how to use it after load a snapshot? I believe it should be
> work, because I could find v8/gc extension in that list after load the
> same snapshot.
The gc extension is special cased by the serializer/deserializer. See the line
serialize.cc: Add(ExternalReference::perform_gc_function().address(),
>
> Thanks
>
> On 10月19日, 下午3时45分, Erik Corry <[email protected]> wrote:
>> 2009/10/19 Flier Lu <[email protected]>:
>>
>>
>>
>> > So, do you mean that I need fire a GC before serialize/deserialize
>> > heap? and how can I ensure the GC roots keep same numbers? Are there
>> > any tools could dump the whole heap and make a difference for
>> > troubleshoting?
>>
>> You should try running the debug version of the VM and using the
>> --debug-serialization flag. This will insert tags in the
>> serialization stream which will be checked when deserializing.
>> Looking at where this happens in gdb may tell you where the serializer
>> and the deserializer are getting out of sync. Good luck!
>>
>>
>>
>>
>>
>> > Thanks any way, I think I could try to adjust context later.
>>
>> > On 10月18日, 下午5时25分, Erik Corry <[email protected]> wrote:
>> >> The serialization/deserialization code is very sensitive to what the
>> >> VM has done since it started up. Installing extensions and probably
>> >> many other API calls like context creation etc. will cause garbage
>> >> collection roots to be created. These are traversed when serializing
>> >> and deserializing and if the number of them doesn't match up then you
>> >> will probably get a crash.
>>
>> >> I realize this is not very detailed help. It may help to compile in
>> >> debug mode to get the asserts etc. which could give you more of a clue
>> >> as to what is going on.
>>
>> >> 2009/10/18 Flier Lu <[email protected]>:
>>
>> >> > I'm trying to add serialize/deserialize supports to pyv8, a two-way
>> >> > python and v8 wrapper, base on the v8 internal APIs.
>>
>> >> > Till now, I could dump the snapshot with Serializer.Serialize, but
>> >> > fail to use it to initialize v8 again. The
>> >> > Deserializer::GetContextStack function failed, because the expected
>> >> > format is wrong. I'm confused because the snapshot was generated with
>> >> > same v8 version, even the size seems too smaller (262K) than cctest
>> >> > generated serdes (432K).
>>
>> >> > Could you give me some hints, what I missed when dumping the snapshot?
>> >> > I just refer the test-serialze.cc code and translate it to python
>> >> > wrapper.
>>
>> >> > Thanks
>>
>> >> > # test code with pyv8
>> >> > #!/usr/bin/env python
>> >> > import sys
>>
>> >> > from PyV8 import *
>>
>> >> > if len(sys.argv) == 1:
>> >> > extSrc = """function hello(name) { return "hello " + name + " from
>> >> > javascript"; }"""
>> >> > extJs = JSExtension("hello/javascript", extSrc)
>>
>> >> > JSEngine.serializeEnabled = True
>>
>> >> > with JSContext(extensions=['hello/javascript']) as ctxt:
>> >> > data = JSEngine.serialize()
>>
>> >> > open('snapshot.dat', 'wb').write(data)
>>
>> >> > print "write %d bytes to snapshot.dat" % len(data)
>> >> > else:
>> >> > data = open(sys.argv[1], 'rb').read()
>>
>> >> > print "read %d bytes from %s" % (len(data), sys.argv[1])
>>
>> >> > raw_input()
>>
>> >> > JSEngine.deserialize(data)
>>
>> >> > with JSContext() as ctxt:
>> >> > print ctxt.eval("hello('flier')")
>>
>> >> > # implementation code in pyv8
>> >> > #http://code.google.com/p/pyv8/source/browse/trunk/src/Engine.cpp
>> >> > py::object CEngine::Serialize(void)
>> >> > {
>> >> > v8::internal::byte* data = NULL;
>> >> > int size = 0;
>>
>> >> > Py_BEGIN_ALLOW_THREADS
>>
>> >> > v8::internal::StatsTable::SetCounterFunction
>> >> > (&CEngine::CounterLookup);
>>
>> >> > v8::internal::Serializer serializer;
>>
>> >> > serializer.Serialize();
>>
>> >> > serializer.Finalize(&data, &size);
>>
>> >> > Py_END_ALLOW_THREADS
>>
>> >> > py::object obj(py::handle<>(::PyBuffer_New(size)));
>>
>> >> > void *buf = NULL;
>> >> > Py_ssize_t len = 0;
>>
>> >> > if (0 == ::PyObject_AsWriteBuffer(obj.ptr(), &buf, &len) && buf &&
>> >> > len > 0)
>> >> > {
>> >> > memcpy(buf, data, len);
>> >> > }
>> >> > else
>> >> > {
>> >> > obj = py::object();
>> >> > }
>>
>> >> > return obj;
>> >> > }
>> >> > void CEngine::Deserialize(py::object snapshot)
>> >> > {
>> >> > const void *buf = NULL;
>> >> > Py_ssize_t len = 0;
>>
>> >> > if (PyBuffer_Check(snapshot.ptr()))
>> >> > {
>> >> > if (0 != ::PyObject_AsReadBuffer(snapshot.ptr(), &buf, &len))
>> >> > {
>> >> > buf = NULL;
>> >> > }
>> >> > }
>> >> > else if(PyString_CheckExact(snapshot.ptr()) || PyUnicode_CheckExact
>> >> > (snapshot.ptr()))
>> >> > {
>> >> > if (0 != ::PyString_AsStringAndSize(snapshot.ptr(), (char **)&buf,
>> >> > &len))
>> >> > {
>> >> > buf = NULL;
>> >> > }
>> >> > }
>>
>> >> > if (buf && len > 0)
>> >> > {
>> >> > Py_BEGIN_ALLOW_THREADS
>>
>> >> > v8::internal::Deserializer deserializer((const v8::internal::byte
>> >> > *) buf, len);
>>
>> >> > deserializer.GetFlags();
>>
>> >> > v8::internal::V8::Initialize(&deserializer);
>>
>> >> > Py_END_ALLOW_THREADS
>> >> > }
>> >> > }
>>
>> >> > # error message when execute the test code
>> >> > #
>> >> > # Fatal error in d:\javascript\google-v8\src\serialize.h, line 221
>> >> > # CHECK(c == expected) failed
>> >> > #
>>
>> >> > # call stack for error
>> >> >> _PyV8.pyd!v8::internal::OS::DebugBreak() Line 882 C++
>> >> > _PyV8.pyd!v8::internal::OS::Abort() Line 877 C++
>> >> > _PyV8.pyd!V8_Fatal(const char * file=0x1052ddfc, int line=221,
>> >> > const
>> >> > char * format=0x10527e68, ...) Line 57 C++
>> >> > _PyV8.pyd!CheckHelper(const char * file=0x1052ddfc, int line=221,
>> >> > const char * source=0x1052e0bc, bool condition=false) Line 62 + 0x16
>> >> > bytes C++
>> >> > _PyV8.pyd!v8::internal::SnapshotReader::ExpectC(char
>> >> > expected='C')
>> >> > Line 221 + 0x22 bytes C++
>> >> > _PyV8.pyd!v8::internal::Deserializer::GetContextStack() Line
>> >> > 1595 C+
>> >> > +
>> >> > _PyV8.pyd!v8::internal::Deserializer::Deserialize() Line 1431
>> >> > C++
>> >> >
>> >> > _PyV8.pyd!v8::internal::V8::Initialize(v8::internal::Deserializer *
>> >> > des=0x0021f300) Line 106 C++
>> >> > _PyV8.pyd!CEngine::Deserialize(boost::python::api::object
>> >> > snapshot=
>> >> > {...}) Line 182 + 0xc bytes C++
>> >> > _PyV8.pyd!boost::python::detail::invoke<int,void (__cdecl*)
>> >> > (boost::python::api::object),boost::python::arg_from_python<boost::python::
>> >> > api::object>
>> >> >>(boost::python::detail::invoke_tag_<1,0> __formal={...},
>> >> > boost::python::detail::invoke_tag_<1,0> __formal={...}, void
>> >> > (boost::python::api::object)* & f=0x101a8cf4,
>> >> > boost::python::arg_from_python<boost::python::api::object> & ac0=
>> >> > {...}) Line 81 + 0x1f bytes C++
>> >> > _PyV8.pyd!boost::python::detail::caller_arity<1>::impl<void
>> >> > (__cdecl*)
>> >> > (boost::python::api::object),boost::python::default_call_policies,boost::mp
>> >> > l::vector2<void,boost::python::api::object>
>> >> >>::operator()(_object * args_=0x01312610, _object *
>> >> > __formal=0x00000000) Line 223 + 0x37 bytes C++
>> >> > _PyV8.pyd!
>> >> > boost::python::objects::caller_py_function_impl<boost::python::detail::call
>> >> > er<void
>> >> > (__cdecl*)
>> >> > (boost::python::api::object),boost::python::default_call_policies,boost::mp
>> >> > l::vector2<void,boost::python::api::object>
>> >> >> >::operator()(_object * args=0x01312610, _object * kw=0x00000000)
>> >> > Line 39 C++
>> >> >
>> >> > _PyV8.pyd!boost::python::objects::py_function::operator()(_object *
>> >> > args=0x01312610, _object * kw=0x00000000) Line 144 C++
>> >> > _PyV8.pyd!boost::python::objects::function::call(_object *
>> >> > args=0x01312610, _object * keywords=0x00000000) Line 226 + 0x24 bytes
>> >> > C++
>> >> > _PyV8.pyd!boost::python::objects::`anonymous
>> >> > namespace'::bind_return::operator()() Line 581 + 0x19 bytes C++
>> >> > _PyV8.pyd!
>> >> > boost::detail::function::void_function_ref_invoker0<boost::python::objects:
>> >> > :`anonymous
>> >> > namespace'::bind_return,void>::invoke
>> >> > (boost::detail::function::function_buffer & function_obj_ptr={...})
>> >> > Line 189 C++
>> >> > _PyV8.pyd!boost::function0<void>::operator()() Line 1013 + 0x14
>> >> > bytes C++
>> >> >
>> >> > _PyV8.pyd!boost::python::detail::exception_handler::operator()(const
>> >> > boost::function0<void> & f={...}) Line 75 C++
>> >> > _PyV8.pyd!
>> >> > boost::python::detail::translate_exception<CJavascriptException,void
>> >> > (__cdecl*)(CJavascriptException const &)>::operator()(const
>> >> > boost::python::detail::exception_handler & handler={...}, const
>> >> > boost::function0<void> & f={...}, void (const CJavascriptException &)*
>> >> > const translate=0x101a98a2) Line 46 + 0xc bytes C++
>> >> > _PyV8.pyd!
>> >> > boost::_bi::list3<boost::arg<1>,boost::arg<2>,boost::_bi::value<void
>> >> > (__cdecl*)(CJavascriptException const &)> >::operator()
>> >> > <bool,boost::python::detail::translate_exception<CJavascriptException,void
>> >> > (__cdecl*)(CJavascriptException const &)
>> >> >>,boost::_bi::list2<boost::python::detail::exception_handler const
>> >> > &,boost::function0<void> const &> >(boost::_bi::type<bool> __formal=
>> >> > {...},
>> >> > boost::python::detail::translate_exception<CJavascriptException,void
>> >> > (__cdecl*)(CJavascriptException const &)> & f={...},
>> >> > boost::_bi::list2<boost::python::detail::exception_handler const
>> >> > &,boost::function0<void> const &> & a={...}, boost::_bi::type<bool>
>> >> > __formal={...}) Line 376 C++
>> >> > _PyV8.pyd!
>> >> > boost::_bi::bind_t<bool,boost::python::detail::translate_exception<CJavascr
>> >> > iptException,void
>> >> > (__cdecl*)(CJavascriptException const &)
>> >> >>,boost::_bi::list3<boost::arg<1>,boost::arg<2>,boost::_bi::value<void
>> >> > (__cdecl*)(CJavascriptException const &)> > >::operator()
>> >> > <boost::python::detail::exception_handler,boost::function0<void> >
>> >> > (const boost::python::detail::exception_handler & a1={...}, const
>> >> > boost::function0<void> & a2={...}) Line 103 C++
>> >> > _PyV8.pyd!
>> >> > boost::detail::function::function_obj_invoker2<boost::_bi::bind_t<bool,boos
>> >> > t::python::detail::translate_exception<CJavascriptException,void
>> >> > (__cdecl*)(CJavascriptException const &)
>> >> >>,boost::_bi::list3<boost::arg<1>,boost::arg<2>,boost::_bi::value<void
>> >> > (__cdecl*)(CJavascriptException const &)> >
>> >> >>,bool,boost::python::detail::exception_handler
>>
>> ...
>>
>> 阅读更多 >>
> >
>
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