Seamless server died at windows re-initialization

[stdedos]

Server that died in ​http://xpra.org/trac/ticket/2617#comment:35 gave the attachment as its swan song.

I don't remember doing something else, except interact with the windows or re-initialize them.

[Antoine Martin]

The log seems to indicate that there's an encoder context leak:

Warning: already 25 active instances of <class 'xpra.codecs.enc_x264.encoder.Encoder'>: (x264_encoder(BGRX - 2560x1368), x264_encoder(BGRX - 910x
20), x264_encoder(BGRX - 256x256), x264_encoder(BGRX - 1600x836), x264_encoder(BGRX - 256x256), x264_encoder(BGRX - 1528x724), x264_encoder(BGRX - 256x256), x264_encoder(BGR
X - 256x256), x264_encoder(BGRX - 1528x712), x264_encoder(BGRX - 1528x668), x264_encoder(BGRX - 256x256), x264_encoder(BGRX - 910x20), x264_encoder(BGRX - 1600x836), x264_en
coder(BGRX - 2560x1368), x264_encoder(BGRX - 528x256), x264_encoder(BGRX - 2560x1376), x264_encoder(BGRX - 910x20), x264_encoder(BGRX - 1528x732), x264_encoder(BGRX - 1600x7
32), x264_encoder(BGRX - 256x256), x264_encoder(BGRX - 256x256), x264_encoder(BGRX - 256x256), x264_encoder(BGRX - 910x20), x264_encoder(BGRX - 1528x732), x264_encoder(BGRX 
- 1600x836))

Maybe this is caused by the timeouts that come just before?

2020-06-08 16:40:03,379 Error: expiring 2 missing damage ACKs,
2020-06-08 16:40:03,379  connection may be closed or closing,
2020-06-08 16:40:03,379  sequence numbers missing: 25457, 25458
2020-06-08 16:40:03,387 Error: expiring 2 missing damage ACKs,
2020-06-08 16:40:03,387  connection may be closed or closing,
2020-06-08 16:40:03,389  sequence numbers missing: 21012, 21013
2020-06-08 16:40:03,392 Error: expiring 1 missing damage ACK,
2020-06-08 16:40:03,393  connection may be closed or closing,
2020-06-08 16:40:03,393  sequence numbers missing: 377
2020-06-08 16:40:03,397 Error: expiring 20 missing damage ACKs,
2020-06-08 16:40:03,397  connection may be closed or closing,
2020-06-08 16:40:03,400 Warning: timeout on screen updates for window 1367,
2020-06-08 16:40:03,400  already delayed for more than 61 seconds
2020-06-08 16:40:03,400  sequence numbers missing: 590, 591, 592, 593, 594, 595, 596, 597, 598, 599, 600, 601, 602, 603, 604, 605, 606, 607, 608, 609
2020-06-08 16:40:03,575 client  14 @14.007 server is OK again
2020-06-08 16:41:41,053 client  14 @12.400 server is not responding, drawing spinners over the windows
2020-06-08 16:41:41,089 client  14 @51.521 server is OK again

We should probably flush all pending ACKs when we unmap a window. For OR windows, we'll need another way.