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From "Geir Magnusson Jr." <g...@pobox.com>
Subject Re: [drlvm] HARMONY-1582 - invocation API for DRLVM CHECKPOINT
Date Wed, 04 Oct 2006 12:26:23 GMT
I assume you intend that only the latest patch is applied?  (And I 
assume that it would apply cleanly to SVN HEAD)

geir

Evgueni Brevnov wrote:
> Hi All,
> 
> I have attached updated patch to the JIRA. It should resolve remain
> concerns. Andrey, could you give a green light now?
> 
> Thanks
> Evgueni
> 
> On 10/4/06, Evgueni Brevnov <evgueni.brevnov@gmail.com> wrote:
>> Andrey,
>>
>> I see your points. I think both approaches have advantages and
>> disadvantages. I think it is quite hard to say which approach is
>> better until we play with one VM only. I still feel like introducing
>> one more dependence is better than spreading code which deals with
>> attachment among VM and TM. We really get stuck. OK, just because I
>> want to move forward I will do required changes to remove
>> vm_create_jthread from TM. I believe that will resolve all our
>> disagreements and the patch will be applied soon.
>>
>>
>> Thanks
>> Evgueni.
>>
>> On 10/4/06, Andrey Chernyshev <a.y.chernyshev@gmail.com> wrote:
>> > On 10/3/06, Evgueni Brevnov <evgueni.brevnov@gmail.com> wrote:
>> > > On 10/3/06, Andrey Chernyshev <a.y.chernyshev@gmail.com> wrote:
>> > > > On 10/2/06, Evgueni Brevnov <evgueni.brevnov@gmail.com> wrote:
>> > > > > Andrey,
>> > > > >
>> > > > > Just to be clear.... I agree with you it is more convenient if
>> > > > > jthread_create takes JNIEnv instead of JavaVM. It reflects that
>> > > > > current thread has been attached already. Do you think it 
>> makes sense
>> > > > > to get rid of JNIEnv and use jthread_get_JNI_env in that case?
>> > > >
>> > > > The jthread_* layer is designed like if it were a regular JNI
>> > > > application which is meant to be called from the Java code, hence
>> > > > every function on that layer receives JNIenv. We can probably 
>> get rid
>> > > > of the JNEnv parameter for jthread_* functions, assuming that TM 
>> can
>> > > > always extract JNIenv for the current thread with
>> > > > jthread_get_JNI_env().
>> > > > My only concern  would be the performance - once the JNIenv is 
>> already
>> > > > known for the native part of the kernel classes impl, it must be
>> > > > cheaper to pass JNIEnv to TM as an extra parameter rather than 
>> extract
>> > > > it from the TLS again.
>> > > > Other than that, I see no strong advantages in keeping JNIEnv 
>> parameter.
>> > > >
>> > > >
>> > > > > Regarding jthread_attach. I still didn't get your point.... 
>> Clarify it
>> > > > > please if you think jhread_attach should be modified.
>> > > >
>> > > > Sorry for being not clear: I think for jthread_attach, we have 
>> two options:
>> > > > 1) Make JNIEnv input parameter - it must be new JNIEnv that VM
>> > > > pre-allocates for the new Java thread.  jthread_attach would just
>> > > > associate it with the current thread.
>> > > >
>> > > > 2) Obtain JNIEnv via vm_attach() callback. In this case, if
>> > > > vm_attach() callback implementation needs to know for which 
>> JavaVM new
>> > > > JNIenv has to be allocated, then we'll need to add JavaVM as input
>> > > > parameter for jthread_attach().
>> > > > I think both options should be fine, (1) would probably keep TM
>> > > > interface a bit lighter, though (2) may look more closer to the JNI
>> > > > invocation API idea.
>> > > > So I think adding JavaVM specifically for jthread_attach may make
>> > > > sense given the explanation you provided earlier.
>> > > >
>> > > > The concern I would have regarding the proposed jthread_attach
>> > > > implementation is a call to vm_create_jthread() - this call 
>> introduces
>> > > > an extra dependency of TM on vmcore that I'd prefer to be 
>> avoided. In
>> > > > the original version, jthread_attach() was taking jthread 
>> argument of
>> > > > the already prepared j.l.Thread.
>> > >
>> > > I understand your concern. Unfortunately I don't see what we can do
>> > > here. Let me explain. In the beginning you have an unattached native
>> > > thread. To be able to call java code (which is required for
>> > > constructing j.l.Thread instance) the thread should be attached 
>> first.
>> > > To be specific it should be attached to VM by calling vm_attach which
>> > > will return a valid JNIEnv It is valid to use JNI from that moment.
>> > > Obtained JNIEnv can be used to execute java code and create 
>> j.l.Thread
>> > > instance. Since we do vm_attach in jthread_attach we need to do
>> > > vm_create_jthread inside jthread_atach as well.
>> > > Of course it can be an alternative to do vm_attach and
>> > > vm_create_jthread outside of TM right before jthread_attach. Sure it
>> > > will reduce one dependence between VM and TM. But it seems like
>> > > artificial action for me just because of dependency....
>> >
>> > Why do you think it is artificial? I would rather prefer not to throw
>> > vm_attach event from the jthread_attach() call at all than to add
>> > extra dependency. The idea of jthread layer is a Java face to
>> > hythread, it is meant to know either a little or nothing about the
>> > rest of VM. It may be logical to throw vm_attach call from the newly
>> > created thread, because there is no other way to let know VM the new
>> > thread is created. VM attach is a different case - VM already knows
>> > about new Java thread at the time of the AttachCurrentThread call.
>> >
>> > >
>> > > > Do you think it makes sense to replace a single jthread 
>> parameter with
>> > > > a variety of stuff (like thread group, name)? It seems the only
>> > > > purpose of at these args is to be passed back to VM for
>> > > > vm_jthread_create(). I would suggest to change this and try doing
>> > > > either of:
>> > > > 1) Make signature of jthread_attach with 3 args, JavaVM, jthread 
>> and the daemon.
>> > > Why do you want to pass daemon to TM but thread's name and group. 
>> Just
>> > > because current TM doesn't need such information? What if it is
>> > > required to get thread name later? Say by introducing
>> >
>> > I imagine you need a daemon attribute since the TM is still managing
>> > the thread daemonality. TM is not managing thread name and group -
>> > they are all kept on the Java level, hence passing them may be
>> > excessive.
>> >
>> > > jthread_get_name... What will you do in that case? Let me guess you
>> > > will call j.l.Thread.getName. Right. Ok! In that case I see no
>> > > problems to call j.l.Thread.isDaemon. Do you agree? So it doesn't
>> >
>> > As I suggested earlier, the best way to handle daemonality would
>> > probably be in pure Java - in j.l.Thread (or j.l.VMThreadManager) or
>> > whatever. You already lifted it up to the jthread level, but what if
>> > we can go a little bit higher...
>> >
>> > > seems to be a good design to pass only part of the information to
>> > > jthread_atach. Lets look at the signature of AttachCurrentThread. It
>> > > takes exactly these three parameters (daemon, name, group) passed 
>> as a
>> > > structure. I was thinking about having exactly the same structure as
>> > > third parameter of jthread_attach but it occured to be more 
>> convinient
>> > > to pass them seperatly. Although I don't see strong reasons against
>> > > having a structure a third parameter.
>> >
>> > I see. Acually, I would love to keep the jthread_attach func-ty at the
>> > minimum level which will be needed to handle the only data that TM
>> > should be aware of. We need a formal boundary between jthread layer
>> > and vmcore (otherwise jthread won't have a much of sense, one may
>> > consider it just as a convenience set of functions in vmcore which are
>> > doing something with threading).
>> >
>> > >
>> > > > 2) Move the implementation of vm_create_jtrhead() to
>> > > > thread_java_basic.c - could it be written in pure JNI without using
>> > > > internal VM API like class_alloc_new_object()?
>> > >
>> > > Yes, this can be done but it doesn't fix the problem. You still need
>> > > to know about internal constructor of j.l.Thread
>> >
>> > That's bad. Given what you said, now it seems that the most preferable
>> > sequence for AttachCurrentThread impl still would be like:
>> > JNIEnv = vm_attach();
>> > jthread = create_jthread(JNIenv)
>> > jthread_attach(JNIEnv, jthread) // stores JNIEnv and Hythread into
>> > TLS, doesn't call vm_attach any longer.
>> > - this is almost what we had from the beginning...
>> >
>> > Thanks,
>> > Andrey.
>> >
>> > >
>> > >
>> > > Thanks
>> > > Evgueni
>> > > >
>> > > >
>> > > > Thanks,
>> > > > Andrey.
>> > > >
>> > > > >
>> > > > > Thank you
>> > > > > Evgueni
>> > > > >
>> > > > > On 10/2/06, Evgueni Brevnov <evgueni.brevnov@gmail.com>
wrote:
>> > > > > > On 9/29/06, Andrey Chernyshev <a.y.chernyshev@gmail.com>
wrote:
>> > > > > > > On 9/29/06, Evgueni Brevnov <evgueni.brevnov@gmail.com>

>> wrote:
>> > > > > > > > Artem,
>> > > > > > > >
>> > > > > > > > Thank you for your feedback.... find my inlined.....
>> > > > > > > >
>> > > > > > > > On 9/29/06, Artem Aliev <artem.aliev@gmail.com>
wrote:
>> > > > > > > > > Evgueni,
>> > > > > > > > >
>> > > > > > > > > I got most of your changes, but still disagree
with all
>> > > > > > > > > hythread/jthread interface changes. Could
leave 
>> interface unchanged.
>> > > > > > > > > See following possible solutions, that could
solve the 
>> same problems
>> > > > > > > > > without interface changes.
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > 1) daemon attribute is a java specific. (Andrey

>> mentioned this already).
>> > > > > > > > >   Could you please move it back. to the jthread
layer. 
>> It is better
>> > > > > > > > > to rename
>> > > > > > > > >   hythread_wait_for_all_nondaemon_threads()
to
>> > > > > > > > > jthread_wait_for_all_nondaemon_threads().
>> > > > > > > > Ok, I see no problems to move "daemon" to java
layer. In 
>> that case:
>> > > > > > > > 1) I will move hythread_wait_for_all_nondaemon_threads()

>> from
>> > > > > > > > thread_init.c to one which implements java layer.
>> > > > > > > > 2) I will move daemon field from HyThread structure.
>> > > > > > > >
>> > > > > > > > Agree?
>> > > > > > >
>> > > > > > > Sounds good to me.
>> > > > > >
>> > > > > > OK, will do that.
>> > > > > >
>> > > > > > >
>> > > > > > >
>> > > > > > > >
>> > > > > > > > >
>> > > > > > > > > 2)  JavaVM could be retrieved  from JNIEnv
by  
>> jni_get_java_vm(). So
>> > > > > > > > > let the jthread_create() and others to use
JNIEnv 
>> (that is passed from
>> > > > > > > > > java native method).
>> > > > > > > > > The vm_attach could get old JNI env and create
new one 
>> for the new thread.
>> > > > > > > > > The first JNIEnv is created in CreateVM call
and could 
>> be passed to
>> > > > > > > > > the first thread at startup.
>> > > > > > > > No, no, no. I completely disagree with that!!!
Why do 
>> you like JNIEnv
>> > > > > > > > but JavaVM. Why do you think that passing JavaVM
instead 
>> of JNIEnv
>> > > > > > > > makes TM less modular? I don't see any difference

>> here.... It seems
>> > > > > > > > for me like a big big hack to grab JNIEnv from
another 
>> thread and pass
>> > > > > > > > it to jthread_attach to perform operations in
the 
>> current thread.
>> > > > > > >
>> > > > > > > TM needs to know JNIEnv, mainly for managing the 
>> references to
>> > > > > > > objects, throwing exceptions and calling run() method
of a 
>> new thread.
>> > > > > > > JNI spec proposes that JNIEnv is valid within the given

>> thread, this
>> > > > > > > is why TM holds the JNIEnv pointer at the moment. This
is 
>> why TM likes
>> > > > > > > the JNIEnv.
>> > > > > > >
>> > > > > > > Having the JNIEnv, one is able to get JavaVM but not
vise 
>> versa. This
>> > > > > > > is why TM doesn't like the JavaVM :)
>> > > > > > I see your point. Only one note this is true for already

>> attached threads...
>> > > > > >
>> > > > > > >
>> > > > > > > I agree with you that there is a design flaw that the

>> JNIEnv is copied
>> > > > > > > from the parent thread to a child thread during thread

>> creation. I
>> > > > > > > think it could be resolved via vm_attach() hook - with

>> this event, VM
>> > > > > > > might tell the TM what the JNIEnv pointer for new thread

>> should be. I
>> > > > > > > think you did that by extending the vm_attach() call
with 
>> the JNIEnv**
>> > > > > > > argument.
>> > > > > > >
>> > > > > > > What is not completely clear is, why do you have to
pass 
>> the JavaVM
>> > > > > > > forth and back, once from VM to TM, and then back from
TM 
>> to VM again?
>> > > > > > >
>> > > > > > > If you need to know in jthread_attach, which particular
VM 
>> vm_attach()
>> > > > > > > event is coming from, you could have vm_attach like
>> > > > > > > vm_attach(JNIEnv* currentThreadEnv,  JNIEnv** newThreadEnv).
>> > > > > > I'm a little bit confused.....Current thread hasn't been

>> attached yet.
>> > > > > > So there is no JNIEnv for it yet. How it can be passed as

>> the first
>> > > > > > parameter to vm_attach()?
>> > > > > >
>> > > > > > > Then you will be always able to get the JavaVM from
the 
>> JNIEnv.
>> > > > > > > The only difference is that you are currently doing

>> JNIEnv->JavaVM
>> > > > > > > conversion in the VMThreadManager, but why can't you
just 
>> do this in
>> > > > > > > vm_attach() without changing the interface of the TM?
>> > > > > > > So far JavaVM really looks like an extra knowledge
that TM 
>> doesn't
>> > > > > > > have to be aware of.
>> > > > > > >
>> > > > > > > > Moreover there is no JNIEnv when main thread attaches
to 
>> VM. So we
>> > > > > > > > should either keep it as is or change original
design of 
>> TM and attach
>> > > > > > > > thread to VM before attaching it to TM. In that
case we 
>> will have
>> > > > > > > > valid JNIEnv which can be passed to jthread_atatch.
We 
>> need to think
>> > > > > > > > over it twice before changing something....
>> > > > > > >
>> > > > > > > Right. For jthread_attach, JNIenv needs to be changed
from 
>> being input
>> > > > > > > parameter to being the output parameter. The way how

>> JNIenv is
>> > > > > > > obtained by TM should be vm_attach() event.
>> > > > > > OK, JNIEnv is output parameter. And it obtained by 
>> vm_attach(). This
>> > > > > > is exactly like I do in the patch. What I don't understand

>> is how
>> > > > > > jthread_attach knows to which VM the thread should be 
>> attached? Do you
>> > > > > > suggest calling vm_attach first to create JNIEnv it pass
it to
>> > > > > > jthread_attach?
>> > > > > >
>> > > > > > >
>> > > > > > > >
>> > > > > > > >
>> > > > > > > >
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > 4) Original classlib hythread do not use

>> hythread_library_t in arguments,
>> > > > > > > > > It uses following code:
>> > > > > > > > >
>> > > > > > > > >  hythread_library_t lib = GLOBAL_DATA (default_library);
>> > > > > > > > > or
>> > > > > > > > >  hythread_library_t library = thread->library;
>> > > > > > > > >
>> > > > > > > > > So could you please use the same mechanism
and remove 
>> hythread_*_ex >functions.
>> > > > > > > > Let's see if classlib's hythread needs changing
first. 
>> It seems for me
>> > > > > > > > such code prevents us from having multi VM.
>> > > > > > > >
>> > > > > > > > >
>> > > > > > > > > 5. You introduce more then one jni env, but
still use 
>> global variable for it.
>> > > > > > > > > So all changes like following:
>> > > > > > > > > -    JNIEnv *jenv = (JNIEnv*)jni_native_intf;
>> > > > > > > > > +    JNIEnv *jenv = jni_native_intf;
>> > > > > > > > >
>> > > > > > > > > should be like:
>> > > > > > > > > -    JNIEnv *jenv = (JNIEnv*)jni_native_intf;
>> > > > > > > > > +    JNIEnv *jenv = get_jni_env(jthread_self());
>> > > > > > > >
>> > > > > > > > Ok, I see. I agree that global jni_native_intf
should 
>> not be used.
>> > > > > > > > There was simple reason why I altered such lines.

>> Because I changed
>> > > > > > > > the type of  jni_native_intf and no casting operator
is 
>> needed now. To
>> > > > > > > > be honest I think get_jni_env(jthread_self())
can be 
>> good as temporary
>> > > > > > > > solution only. Lets wait for design of multi VM
and fix 
>> it according
>> > > > > > > > to it.
>> > > > > > >
>> > > > > > > While we are in JNI code, we always have the JNIenv
(at least
>> > > > > > > initially it comes from Java code). If we consider
VM code 
>> as if it
>> > > > > > > was a JNI application, then it seems like we should
be 
>> just passing
>> > > > > > > JNIEnv as a parameter to all functions in VM. Or, we
can 
>> be taking it
>> > > > > > > from TLS (via jthread_self()), depending on which way
is 
>> faster...
>> > > > > > Agree.
>> > > > > >
>> > > > > > >
>> > > > > > > >
>> > > > > > > > >
>> > > > > > > > > 6). And small remarks:
>> > > > > > > > > +jint vm_init1(JavaVM_Internal * java_vm,

>> JavaVMInitArgs * vm_arguments);
>> > > > > > > > > +jint vm_init2(JNIEnv_Internal * jni_env);
>> > > > > > > > > Could you make names more meaningful, then
1,2,3...?
>> > > > > > > > Ok, will do that.
>> > > > > > > >
>> > > > > > > > >
>> > > > > > > > > class VM_thread {
>> > > > > > > > > ...
>> > > > > > > > > +    JNIEnv_Internal * jni_env;
>> > > > > > > > > The jthread already has the jni_env pointer,
you do 
>> not need to
>> > > > > > > > > duplicate it here.
>> > > > > > > > > forexample by using jthread_get_JNI_env(jthread_self());
>> > > > > > > >
>> > > > > > > > Yes I know. I don't see any problems here. Some
times it 
>> is much more
>> > > > > > > > convenient to get JNIEnv from VM_thread structure
(and 
>> faster) instead
>> > > > > > > > of doing jthread_get_JNI_env(jthread_self()).
So I need 
>> strong
>> > > > > > > > arguments for removing it. Again it seems that
should be 
>> addressed in
>> > > > > > > > design of multi VM. So lets forget about it for
a while...
>> > > > > > >
>> > > > > > > I think that the data duplication would always serve
as a 
>> potential
>> > > > > > > source of errors - while updating one copy of object,
you 
>> may forget
>> > > > > > > to update the other, often resulting into a strange

>> behavior of the
>> > > > > > > whole application. Let's see what are the specific

>> performance
>> > > > > > > concerns that have to be addressed. To get VM_thread

>> structure, you
>> > > > > > > would eventually go to the TLS, just like
>> > > > > > > jthread_get_JNI_env(jthread_self() would do.
>> > > > > > If there is already VM_thread structure for some reasons

>> then there
>> > > > > > will be no extra access to TLS. It is definitely much more
in
>> > > > > > jthread_get_JNI_env(jthread_self() than just one TLS access

>> and one
>> > > > > > dereferncing. I don't think it is a really big problem now.

>> Do you
>> > > > > > agree to look at this later. I guess multi VM implementation

>> will
>> > > > > > alter it in any case.
>> > > > > >
>> > > > > > Thanks
>> > > > > > Evgueni
>> > > > > >
>> > > > > > >
>> > > > > > > Thanks,
>> > > > > > > Andrey.
>> > > > > > >
>> > > > > > > >
>> > > > > > > > Evgueni
>> > > > > > > > >
>> > > > > > > > > Thanks
>> > > > > > > > > Artem
>> > > > > > > > >
>> > > > > > > > > On 9/28/06, Evgueni Brevnov 
>> <evgueni.brevnov@gmail.com> wrote:
>> > > > > > > > > > I suppose two days silence means that
there is no 
>> objects (maybe
>> > > > > > > > > > interest) against proposed patch. I
would suggest to 
>> commit it ASAP.
>> > > > > > > > > > It really works! There are some cases
when current 
>> VM crashes but the
>> > > > > > > > > > patch fixes it. I can work on bringing
cunit tests 
>> to live as soon as
>> > > > > > > > > > the patch is committed.... This is just
my 
>> understanding.
>> > > > > > > > > >
>> > > > > > > > > > Thanks
>> > > > > > > > > > Evgueni
>> > > > > > > > > >
>> > > > > > > > > > On 9/28/06, Geir Magnusson Jr. <geir@pobox.com>
wrote:
>> > > > > > > > > > > So where are we here?
>> > > > > > > > > > >
>> > > > > > > > > > > On Sep 28, 2006, at 12:41 AM, Evgueni
Brevnov wrote:
>> > > > > > > > > > >
>> > > > > > > > > > > > On 9/28/06, Weldon Washburn

>> <weldonwjw@gmail.com> wrote:
>> > > > > > > > > > > >> On 9/26/06, Evgueni Brevnov

>> <evgueni.brevnov@gmail.com> wrote:
>> > > > > > > > > > > >> >
>> > > > > > > > > > > >> > On 9/27/06, Andrey
Chernyshev 
>> <a.y.chernyshev@gmail.com> wrote:
>> > > > > > > > > > > >> > > (3)
>> > > > > > > > > > > >> > > One more lock
is added - hythread_lib_lock. 
>> How is that differ
>> > > > > > > > > > > >> from
>> > > > > > > > > > > >> > > the hythread_global_lock
that we already 
>> have? Each extra lock
>> > > > > > > > > > > >> to the
>> > > > > > > > > > > >> > > system may add
more possibilities for 
>> deadlocks, as well as can
>> > > > > > > > > > > >> > > negatively impact
the scalability (unless 
>> some of the existing
>> > > > > > > > > > > >> locks
>> > > > > > > > > > > >> > > are split).
>> > > > > > > > > > > >> > hythread_lib_lock
acquires exactly the same 
>> lock as
>> > > > > > > > > > > >> > hythread_global_lock.
Probably I miss 
>> something but we need to be
>> > > > > > > > > > > >> > compatible with IBM
threading library now. 
>> This library has such
>> > > > > > > > > > > >> > function. That's
why I added it. Sounds right?
>> > > > > > > > > > > >>
>> > > > > > > > > > > >>
>> > > > > > > > > > > >> Well,  this sort of, kind
of sounds right but 
>> not quite.  Its a
>> > > > > > > > > > > >> little more
>> > > > > > > > > > > >> subtle than being compatible
with IBM threading 
>> library.  The
>> > > > > > > > > > > >> first goal is
>> > > > > > > > > > > >> to identify the parts
of IBM threading library 
>> that are JVM
>> > > > > > > > > > > >> independent.  It
>> > > > > > > > > > > >> makes sense for DRLVM
to be compatible with the 
>> independent
>> > > > > > > > > > > >> parts.   This
>> > > > > > > > > > > >> should be a nobrainer.
>> > > > > > > > > > > >>
>> > > > > > > > > > > >> The parts of IBM threading
library that assume 
>> a specific JVM
>> > > > > > > > > > > >> implementation
>> > > > > > > > > > > >> will be a problem.  We
will need to find a 
>> solution that is
>> > > > > > > > > > > >> endorsed by all
>> > > > > > > > > > > >> the stakeholders (including
J9 folks).  The 
>> hythread_global_lock
>> > > > > > > > > > > >> falls into
>> > > > > > > > > > > >> this category.  For starts,
I would like to see 
>> a concise
>> > > > > > > > > > > >> description from
>> > > > > > > > > > > >> the portlib owners on
what hythread_global_lock 
>> protects, which
>> > > > > > > > > > > >> locks have
>> > > > > > > > > > > >> to be held before grabbing
this lock, are there 
>> any restrictions
>> > > > > > > > > > > >> on what
>> > > > > > > > > > > >> system calls can be made
while holding this 
>> lock (like sleep or
>> > > > > > > > > > > >> wait), etc.
>> > > > > > > > > > > >
>> > > > > > > > > > > > Weldon, I completely agree
with what your are 
>> saying. It's common
>> > > > > > > > > > > > problem of current hythread
that should be 
>> resolved some how. I just
>> > > > > > > > > > > > go inline with current implementation
and added 
>> two missing functions.
>> > > > > > > > > > > > Missing these can lead to
the same problems as 
>> with hythread_exit
>> > > > > > > > > > > > discussed  in another thread
"[drlvm] [launcher] 
>> Executable hangs".
>> > > > > > > > > > > >
>> > > > > > > > > > > >>
>> > > > > > > > > > > >> To get a better idea what's
in the patch.diff, 
>> I printed it out.
>> > > > > > > > > > > >> Its 120+
>> > > > > > > > > > > >> pages.  Quite a big patch!
 Most of it looks 
>> like straight forward
>> > > > > > > > > > > >> JNI
>> > > > > > > > > > > >> interface glue.  There
are some tricky parts.  
>> I would like to
>> > > > > > > > > > > >> know the
>> > > > > > > > > > > >> design review process
for these parts.  Using 
>> grep, I found 20
>> > > > > > > > > > > >> locations
>> > > > > > > > > > > >> where ...suspend_enable...
and 
>> ...suspend_disable... have been
>> > > > > > > > > > > >> added.  And
>> > > > > > > > > > > >> 25 locations where enable/disable
have been 
>> removed.  Failure in
>> > > > > > > > > > > >> this logic
>> > > > > > > > > > > >> can lead to incorrect
reference pointer 
>> enumeration.  These are
>> > > > > > > > > > > >> probably the
>> > > > > > > > > > > >> hardest bugs to find.
 Please tell us who has 
>> looked at this code
>> > > > > > > > > > > >> in depth.
>> > > > > > > > > > > > Only me and you :-) Honetsly
I think it happpens 
>> now....
>> > > > > > > > > > > >
>> > > > > > > > > > > >> Are there any known design
flaws in it?
>> > > > > > > > > > > > I can think of two possible
problems we may want 
>> to discuss.
>> > > > > > > > > > > > 1) Should native threads have
"daemon" status or 
>> its completely java
>> > > > > > > > > > > > notion? This is TM related
thing.
>> > > > > > > > > > > > 2) Should we attach thread
to VM before 
>> attaching it to TM by calling
>> > > > > > > > > > > > jthread_atatch OR jthread_attach
should callback 
>> VM to attach a thread
>> > > > > > > > > > > > to it? I didn't change original
design of TM 
>> here ...... it implements
>> > > > > > > > > > > > second choice.
>> > > > > > > > > > > >
>> > > > > > > > > > > >>
>> > > > > > > > > > > >> I also notice APIs called
tmn_suspend_enable(),
>> > > > > > > > > > > >> hythread_suspend_enable()
>> > > > > > > > > > > >> -- are these simply different
names for the 
>> same binary
>> > > > > > > > > > > >> executible.  Or
>> > > > > > > > > > > >> different binaries that
do the same thing??
>> > > > > > > > > > > >
>> > > > > > > > > > > > No, this is not just different
names. 
>> tm_suspend_enable asserts that
>> > > > > > > > > > > > thread is in disabled state
before calling 
>> hythread_suspend_enable (in
>> > > > > > > > > > > > debug mode only).
>> > > > > > > > > > > >
>> > > > > > > > > > > > Thanks
>> > > > > > > > > > > > Evgueni
>> > > > > > > > > > > >>
>> > > > > > > > > > > >>
>> > > > > > > > > > > >> --
>> > > > > > > > > > > >> > Weldon Washburn
>> > > > > > > > > > > >> > Intel Middleware
Products Division
>> > > > > > > > > > > >>
>> > > > > > > > > > > >>
>> > > > > > > > > > > >
>> > > > > > > > > > > > 
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