Writing fp-info-cache temp file take too long over networked FS (e.g. samba)

[aaa]

Hi,

Application: Pcbnew
Version: 5.1.5-52549c5~84~ubuntu18.04.1, release build
Libraries:
    wxWidgets 3.0.4
    libcurl/7.58.0 OpenSSL/1.1.1 zlib/1.2.11 libidn2/2.0.4 libpsl/0.19.1 (+libidn2/2.0.4) nghttp2/1.30.0 librtmp/2.3
Platform: Linux 4.15.0-20-generic x86_64, 64 bit, Little endian, wxGTK
Build Info:
    wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.22
    Boost: 1.65.1
    OpenCASCADE Community Edition: 6.9.1
    Curl: 7.58.0
    Compiler: GCC 7.4.0 with C++ ABI 1011

Build settings:
    USE_WX_GRAPHICS_CONTEXT=OFF
    USE_WX_OVERLAY=ON
    KICAD_SCRIPTING=ON
    KICAD_SCRIPTING_MODULES=ON
    KICAD_SCRIPTING_PYTHON3=ON
    KICAD_SCRIPTING_WXPYTHON=ON
    KICAD_SCRIPTING_WXPYTHON_PHOENIX=ON
    KICAD_SCRIPTING_ACTION_MENU=ON
    BUILD_GITHUB_PLUGIN=ON
    KICAD_USE_OCE=ON
    KICAD_USE_OCC=OFF
    KICAD_SPICE=ON

When closing either Footprint Editor or pcbnew, fp-info-cache<random> temp file is written from scratch line-by-line into the project's directory. This is fine when the project directory is on a local filesystem. However, if the project directory is on a samba share, writing the whole file can take literally a minute. This means that the application window is not refreshing and it seems like it hung. This is annoying when you are editing a footprint and forget about this behaviour and 'accidentally' close the footprint editor. You have to wait a minute for the fp-info-cache<random> file to get completely written before you can continue working with kicad.

Looking at the samba server logs, the fp-info-cache<random> is written line by line and each write is sent as a separate request:

[2019/12/07 23:18:11.740618, 3] ../source3/smbd/smb2_write.c:212(smb2_write_complete_internal)
  smb2: fnum 2023785553, file plosaky/polizei_rx/polizei_rx/fp-info-cache0bIzQY, length=2 offset=0 wrote=2
[2019/12/07 23:18:11.741681, 3] ../source3/smbd/smb2_write.c:212(smb2_write_complete_internal)
  smb2: fnum 2023785553, file plosaky/polizei_rx/polizei_rx/fp-info-cache0bIzQY, length=2 offset=0 wrote=2
[2019/12/07 23:18:11.742641, 3] ../source3/smbd/smb2_write.c:212(smb2_write_complete_internal)
  smb2: fnum 2023785553, file plosaky/polizei_rx/polizei_rx/fp-info-cache0bIzQY, length=9 offset=0 wrote=9
[2019/12/07 23:18:11.744346, 3] ../source3/smbd/smb2_write.c:212(smb2_write_complete_internal)
  smb2: fnum 2023785553, file plosaky/polizei_rx/polizei_rx/fp-info-cache0bIzQY, length=30 offset=0 wrote=30
[2019/12/07 23:18:11.745263, 3] ../source3/smbd/smb2_write.c:212(smb2_write_complete_internal)
  smb2: fnum 2023785553, file plosaky/polizei_rx/polizei_rx/fp-info-cache0bIzQY, length=52 offset=0 wrote=52
[2019/12/07 23:18:11.746235, 3] ../source3/smbd/smb2_write.c:212(smb2_write_complete_internal)
  smb2: fnum 2023785553, file plosaky/polizei_rx/polizei_rx/fp-info-cache0bIzQY, length=14 offset=0 wrote=14
[2019/12/07 23:18:11.747096, 3] ../source3/smbd/smb2_write.c:212(smb2_write_complete_internal)
  smb2: fnum 2023785553, file plosaky/polizei_rx/polizei_rx/fp-info-cache0bIzQY, length=2 offset=0 wrote=2

In general, writing one fp-info-cache<random> file, with the default set of footprint libraries, can produce ~75k individual writes over the network, in this case:

[ /var/log/samba ]# cat log. | grep fp-info-cache0bIzQY | grep wrote | wc -l
75048
[ /var/log/samba ]# wc -l /mnt/data/ostatne/plosaky/polizei_rx/polizei_rx/fp-info-cache
75048 /mnt/data/ostatne/plosaky/polizei_rx/polizei_rx/fp-info-cache

..and take more than a minute:

[/var/log/samba ]# cat log. | grep fp-info-cache0bIzQY -B1 | head -2
[2019/12/07 23:16:56.293527, 2] ../source3/smbd/open.c:1006(open_file)
  peter opened file plosaky/polizei_rx/polizei_rx/fp-info-cache0bIzQY read=Yes write=Yes (numopen=1)
[ /var/log/samba ]# cat log. | grep fp-info-cache0bIzQY -B1 | tail -2
[2019/12/07 23:18:12.022399, 3] ../source3/smbd/reply.c:6777(rename_internals_fsp)
  rename_internals_fsp: succeeded doing rename on plosaky/polizei_rx/polizei_rx/fp-info-cache0bIzQY -> plosaky/polizei_rx/polizei_rx/fp-info-cache

I have not find a way to fine tune the samba server/client to improve the write times. I believe there is not a way to do it, since the file is written line-by-line as separate write requests.

Is there a better way for kicad to write the fp-info-cache<random> file?

Perhaps writing the fp-info-cache<random> file first into an OS temp directory (assuming the OS temp dir is almost always on a local drive, thus very fast) and then, once the fp-info-cache<random> file is completely written in the temp directory, copy the file from the temp dir ectory to the project's directory? The copy operation would be done in a few (one?) network file system write command(s).

Thanks,
Peter