race in xshm image wrapper and video compression?

[totaam]

Issue migrated from trac ticket # 978

component: server | priority: major | resolution: worksforme

2015-09-07 09:09:34: antoine created the issue

---

I believe I hit this bug after a suspend + resume cycle at the "wrong" time, we failed to capture the window pixels:

error processing encode queue: failed to get pixels from XShmImageWrapper(BGRX: 17, 2, 960, 792)
Traceback (most recent call last):
  File "/usr/lib64/python2.7/site-packages/xpra/server/window_source.py", line 1296, in encode_from_queue
    self.make_data_packet_cb(*item)
  File "/usr/lib64/python2.7/site-packages/xpra/server/window_source.py", line 1325, in make_data_packet_cb
    packet = self.make_data_packet(damage_time, process_damage_time, wid, image, coding, sequence, options, flush)
  File "/usr/lib64/python2.7/site-packages/xpra/server/window_source.py", line 1674, in make_data_packet
    ret = encoder(coding, image, options)
  File "/usr/lib64/python2.7/site-packages/xpra/server/window_video_source.py", line 1277, in video_encode
    ret = self._video_encoder.compress_image(csc_image, quality, speed, options)
  File "xpra/codecs/nvenc4/encoder.pyx", line 1841, in xpra.codecs.nvenc4.encoder.Encoder.compress_image (xpra/codecs/nvenc4/encoder.c:20464)
    return self.do_compress_image(image, options)
  File "xpra/codecs/nvenc4/encoder.pyx", line 1868, in xpra.codecs.nvenc4.encoder.Encoder.do_compress_image (xpra/codecs/nvenc4/encoder.c:21116)
    assert pixels, "failed to get pixels from %s" % image
AssertionError: failed to get pixels from XShmImageWrapper(BGRX: 17, 2, 960, 792)

Which means that the pixels ptr was NULL, which should never happen whilst we're still processing the image wrapper.

[totaam]

2015-10-23 07:37:34: antoine changed status from new to assigned

[totaam]

2015-10-23 07:37:34: antoine commented

---

I believe I have also seen this same error with enc_x264 whilst re-sizing the display as part of #976.
It should be very rare, and not fatal, so I'm not going to worry too much about it for now.

[totaam]

2016-07-12 17:51:51: antoine commented

---

Milestone renamed

[totaam]

2016-08-21 10:55:50: antoine commented

---

Milestone renamed

[totaam]

2016-09-27 10:33:25: antoine changed status from assigned to closed

[totaam]

2016-09-27 10:33:25: antoine set resolution to worksforme

[totaam]

2016-09-27 10:33:25: antoine commented

---

Not seen since.