[Libguestfs] [PATCH libnbd 3/3] examples: copy-libev.c: Support extents

[Richard W.M. Jones]

On Mon, Mar 08, 2021 at 01:26:44AM +0200, Nir Soffer wrote:
> $ strace -f -c ../copy/nbdcopy --sparse=1048576 --request-size=1048576
> --requests=16 --connections=1 $SRC $DST
> strace: Process 1094611 attached
> strace: Process 1094612 attached
> strace: Process 1094613 attached
> strace: Process 1094614 attached
> strace: Process 1094615 attached
> strace: Process 1094616 attached
> strace: Process 1094617 attached
> strace: Process 1094618 attached
> strace: Process 1094619 attached
> strace: Process 1094620 attached
> strace: Process 1094621 attached
> strace: Process 1094622 attached
> strace: Process 1094623 attached
> strace: Process 1094641 attached
> 
> (Not sure why we start so many threads with --connections=1 - bug?)

I'm not sure of the exact command, so I used:

  $ ./run nbdcopy --sparse=1048576 --request-size=1048576 --requests=16 --connections=1 -- [ qemu-nbd -f qcow2 -t ~/fedora-32.qcow2 ] [ nbdkit memory 6G ]

Temporarily adding -v shows:

  nbdcopy: src: nbd_ops "qemu-nbd"
  nbdcopy: src: size=6442450944
  nbdcopy: dst: nbd_ops "nbdkit"
  nbdcopy: dst: size=6442450944
  nbdcopy: connections=1 requests=16 threads=1 synchronous=false
                                     ^^^^^^^^^

Many threads were created but they all appeared to be associated with
the ./run script, qemu-nbd and nbdkit.  nbdcopy should only create one
worker thread in this scenario.

Rich.

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