Re: [Qemu-devel] [PATCH 3/3] Add a 'name' parameter to qemu_thread_create

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Jan 28, 2014 at 04:12:44PM +0000, Dr. David Alan Gilbert wrote:
> * Michael S. Tsirkin (mst@redhat.com) wrote:
> > On Tue, Jan 28, 2014 at 03:20:39PM +0000, Dr. David Alan Gilbert (git) wrote:
> > > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > > 
> > > If enabled, set the thread name at creation (on GNU systems with
> > >   pthread_set_np)
> > > Fix up all the callers with a thread name
> > > 
> > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > 
> > Thanks for the patch.
> > 
> > It worries me that tool might start assuming specific
> > thread names - this effectively becomes part of
> > management interface.
> >
> > We avoided this in the past except for VCPU threads -
> > in particular we only expose thread id for VCPU threads.
> > How about some generic name for non-VCPU threads
> > to avoid this issue?
> 
> Since I'm doing migration development, restriction to VCPU
> threads doesn't help me much.
> 
> Putting big scary warnings somewhere (where?) to say that
> the names aren't guaranteed is all I can think of.
> (I did put that warning in the cover letter).

Maybe in --help output.

> I guess I could change the option name to debug-threads
> to make it clear it's for debug.

Sounds good.

> > Also - should we put VCPU # in the thread name?
> 
> Yeh that's something I could add.
> 
> Dave
> 
> > > ---
> > >  cpus.c                          | 6 +++---
> > >  hw/block/dataplane/virtio-blk.c | 2 +-
> > >  hw/usb/ccid-card-emulated.c     | 8 ++++----
> > >  include/qemu/thread.h           | 2 +-
> > >  libcacard/vscclient.c           | 2 +-
> > >  migration.c                     | 2 +-
> > >  thread-pool.c                   | 2 +-
> > >  ui/vnc-jobs.c                   | 3 ++-
> > >  util/compatfd.c                 | 3 ++-
> > >  util/qemu-thread-posix.c        | 9 +++++++--
> > >  util/qemu-thread-win32.c        | 2 +-
> > >  11 files changed, 24 insertions(+), 17 deletions(-)
> > > 
> > > diff --git a/cpus.c b/cpus.c
> > > index ca4c59f..d519b27 100644
> > > --- a/cpus.c
> > > +++ b/cpus.c
> > > @@ -1125,7 +1125,7 @@ static void qemu_tcg_init_vcpu(CPUState *cpu)
> > >          cpu->halt_cond = g_malloc0(sizeof(QemuCond));
> > >          qemu_cond_init(cpu->halt_cond);
> > >          tcg_halt_cond = cpu->halt_cond;
> > > -        qemu_thread_create(cpu->thread, qemu_tcg_cpu_thread_fn, cpu,
> > > +        qemu_thread_create(cpu->thread, "CPU/TCG", qemu_tcg_cpu_thread_fn, cpu,
> > >                             QEMU_THREAD_JOINABLE);
> > >  #ifdef _WIN32
> > >          cpu->hThread = qemu_thread_get_handle(cpu->thread);
> > > @@ -1145,7 +1145,7 @@ static void qemu_kvm_start_vcpu(CPUState *cpu)
> > >      cpu->thread = g_malloc0(sizeof(QemuThread));
> > >      cpu->halt_cond = g_malloc0(sizeof(QemuCond));
> > >      qemu_cond_init(cpu->halt_cond);
> > > -    qemu_thread_create(cpu->thread, qemu_kvm_cpu_thread_fn, cpu,
> > > +    qemu_thread_create(cpu->thread, "CPU/KVM", qemu_kvm_cpu_thread_fn, cpu,
> > >                         QEMU_THREAD_JOINABLE);
> > >      while (!cpu->created) {
> > >          qemu_cond_wait(&qemu_cpu_cond, &qemu_global_mutex);
> > > @@ -1157,7 +1157,7 @@ static void qemu_dummy_start_vcpu(CPUState *cpu)
> > >      cpu->thread = g_malloc0(sizeof(QemuThread));
> > >      cpu->halt_cond = g_malloc0(sizeof(QemuCond));
> > >      qemu_cond_init(cpu->halt_cond);
> > > -    qemu_thread_create(cpu->thread, qemu_dummy_cpu_thread_fn, cpu,
> > > +    qemu_thread_create(cpu->thread, "CPU/DUMMY", qemu_dummy_cpu_thread_fn, cpu,
> > >                         QEMU_THREAD_JOINABLE);
> > >      while (!cpu->created) {
> > >          qemu_cond_wait(&qemu_cpu_cond, &qemu_global_mutex);
> > > diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
> > > index 456d437..980a684 100644
> > > --- a/hw/block/dataplane/virtio-blk.c
> > > +++ b/hw/block/dataplane/virtio-blk.c
> > > @@ -358,7 +358,7 @@ static void start_data_plane_bh(void *opaque)
> > >  
> > >      qemu_bh_delete(s->start_bh);
> > >      s->start_bh = NULL;
> > > -    qemu_thread_create(&s->thread, data_plane_thread,
> > > +    qemu_thread_create(&s->thread, "data_plane", data_plane_thread,
> > >                         s, QEMU_THREAD_JOINABLE);
> > >  }
> > >  
> > > diff --git a/hw/usb/ccid-card-emulated.c b/hw/usb/ccid-card-emulated.c
> > > index aa913df..7213c89 100644
> > > --- a/hw/usb/ccid-card-emulated.c
> > > +++ b/hw/usb/ccid-card-emulated.c
> > > @@ -546,10 +546,10 @@ static int emulated_initfn(CCIDCardState *base)
> > >          printf("%s: failed to initialize vcard\n", EMULATED_DEV_NAME);
> > >          return -1;
> > >      }
> > > -    qemu_thread_create(&card->event_thread_id, event_thread, card,
> > > -                       QEMU_THREAD_JOINABLE);
> > > -    qemu_thread_create(&card->apdu_thread_id, handle_apdu_thread, card,
> > > -                       QEMU_THREAD_JOINABLE);
> > > +    qemu_thread_create(&card->event_thread_id, "ccid/event", event_thread,
> > > +                       card, QEMU_THREAD_JOINABLE);
> > > +    qemu_thread_create(&card->apdu_thread_id, "ccid/apdu", handle_apdu_thread,
> > > +                       card, QEMU_THREAD_JOINABLE);
> > >      return 0;
> > >  }
> > >  
> > > diff --git a/include/qemu/thread.h b/include/qemu/thread.h
> > > index bf1e110..f7e3b9b 100644
> > > --- a/include/qemu/thread.h
> > > +++ b/include/qemu/thread.h
> > > @@ -52,7 +52,7 @@ void qemu_event_reset(QemuEvent *ev);
> > >  void qemu_event_wait(QemuEvent *ev);
> > >  void qemu_event_destroy(QemuEvent *ev);
> > >  
> > > -void qemu_thread_create(QemuThread *thread,
> > > +void qemu_thread_create(QemuThread *thread, const char *name,
> > >                          void *(*start_routine)(void *),
> > >                          void *arg, int mode);
> > >  void *qemu_thread_join(QemuThread *thread);
> > > diff --git a/libcacard/vscclient.c b/libcacard/vscclient.c
> > > index 24f7088..3477ab3 100644
> > > --- a/libcacard/vscclient.c
> > > +++ b/libcacard/vscclient.c
> > > @@ -269,7 +269,7 @@ on_host_init(VSCMsgHeader *mhHeader, VSCMsgInit *incoming)
> > >      send_msg(VSC_ReaderRemove, VSCARD_MINIMAL_READER_ID, NULL, 0);
> > >      /* launch the event_thread. This will trigger reader adds for all the
> > >       * existing readers */
> > > -    qemu_thread_create(&thread_id, event_thread, NULL, 0);
> > > +    qemu_thread_create(&thread_id, "vsc/event", event_thread, NULL, 0);
> > >      return 0;
> > >  }
> > >  
> > > diff --git a/migration.c b/migration.c
> > > index 7235c23..bddec7e 100644
> > > --- a/migration.c
> > > +++ b/migration.c
> > > @@ -679,6 +679,6 @@ void migrate_fd_connect(MigrationState *s)
> > >      /* Notify before starting migration thread */
> > >      notifier_list_notify(&migration_state_notifiers, s);
> > >  
> > > -    qemu_thread_create(&s->thread, migration_thread, s,
> > > +    qemu_thread_create(&s->thread, "migration", migration_thread, s,
> > >                         QEMU_THREAD_JOINABLE);
> > >  }
> > > diff --git a/thread-pool.c b/thread-pool.c
> > > index 3735fd3..fbdd3ff 100644
> > > --- a/thread-pool.c
> > > +++ b/thread-pool.c
> > > @@ -140,7 +140,7 @@ static void do_spawn_thread(ThreadPool *pool)
> > >      pool->new_threads--;
> > >      pool->pending_threads++;
> > >  
> > > -    qemu_thread_create(&t, worker_thread, pool, QEMU_THREAD_DETACHED);
> > > +    qemu_thread_create(&t, "worker", worker_thread, pool, QEMU_THREAD_DETACHED);
> > >  }
> > >  
> > >  static void spawn_thread_bh_fn(void *opaque)
> > > diff --git a/ui/vnc-jobs.c b/ui/vnc-jobs.c
> > > index 2d3fce8..3f3c47b 100644
> > > --- a/ui/vnc-jobs.c
> > > +++ b/ui/vnc-jobs.c
> > > @@ -333,7 +333,8 @@ void vnc_start_worker_thread(void)
> > >          return ;
> > >  
> > >      q = vnc_queue_init();
> > > -    qemu_thread_create(&q->thread, vnc_worker_thread, q, QEMU_THREAD_DETACHED);
> > > +    qemu_thread_create(&q->thread, "vnc_worker", vnc_worker_thread, q,
> > > +                       QEMU_THREAD_DETACHED);
> > >      queue = q; /* Set global queue */
> > >  }
> > >  
> > > diff --git a/util/compatfd.c b/util/compatfd.c
> > > index 430a41c..341ada6 100644
> > > --- a/util/compatfd.c
> > > +++ b/util/compatfd.c
> > > @@ -88,7 +88,8 @@ static int qemu_signalfd_compat(const sigset_t *mask)
> > >      memcpy(&info->mask, mask, sizeof(*mask));
> > >      info->fd = fds[1];
> > >  
> > > -    qemu_thread_create(&thread, sigwait_compat, info, QEMU_THREAD_DETACHED);
> > > +    qemu_thread_create(&thread, "signalfd_compat", sigwait_compat, info,
> > > +                       QEMU_THREAD_DETACHED);
> > >  
> > >      return fds[0];
> > >  }
> > > diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c
> > > index 0fa6c81..45113b4 100644
> > > --- a/util/qemu-thread-posix.c
> > > +++ b/util/qemu-thread-posix.c
> > > @@ -394,8 +394,7 @@ void qemu_event_wait(QemuEvent *ev)
> > >      }
> > >  }
> > >  
> > > -
> > > -void qemu_thread_create(QemuThread *thread,
> > > +void qemu_thread_create(QemuThread *thread, const char *name,
> > >                         void *(*start_routine)(void*),
> > >                         void *arg, int mode)
> > >  {
> > > @@ -421,6 +420,12 @@ void qemu_thread_create(QemuThread *thread,
> > >      if (err)
> > >          error_exit(err, __func__);
> > >  
> > > +#ifdef _GNU_SOURCE
> > > +    if (name_threads) {
> > > +        pthread_setname_np(thread->thread, name);
> > > +    }
> > > +#endif
> > > +
> > >      pthread_sigmask(SIG_SETMASK, &oldset, NULL);
> > >  
> > >      pthread_attr_destroy(&attr);
> > > diff --git a/util/qemu-thread-win32.c b/util/qemu-thread-win32.c
> > > index e42cb77..b9c957b 100644
> > > --- a/util/qemu-thread-win32.c
> > > +++ b/util/qemu-thread-win32.c
> > > @@ -333,7 +333,7 @@ void *qemu_thread_join(QemuThread *thread)
> > >      return ret;
> > >  }
> > >  
> > > -void qemu_thread_create(QemuThread *thread,
> > > +void qemu_thread_create(QemuThread *thread, const char *name,
> > >                         void *(*start_routine)(void *),
> > >                         void *arg, int mode)
> > >  {
> > > -- 
> > > 1.8.5.3
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK