51 lines
1.8 KiB
Markdown
51 lines
1.8 KiB
Markdown
|
# Parallel transfers
|
||
|
|
|
||
|
|
curl 7.66.0 introduced support for doing multiple transfers simultaneously; in
|
||
|
|
parallel.
|
||
|
|
|
||
|
|
## -Z, --parallel
|
||
|
|
|
||
|
|
When this command line option is used, curl will perform the transfers given
|
||
|
|
to it at the same time. It will do up to `--parallel-max` concurrent
|
||
|
|
transfers, with a default value of 50.
|
||
|
|
|
||
|
|
## Progress meter
|
||
|
|
|
||
|
|
The progress meter that is displayed when doing parallel transfers is
|
||
|
|
completely different than the regular one used for each single transfer.
|
||
|
|
|
||
|
|
It shows:
|
||
|
|
|
||
|
|
o percent download (if known, which means *all* transfers need to have a
|
||
|
|
known size)
|
||
|
|
o percent upload (if known, with the same caveat as for download)
|
||
|
|
o total amount of downloaded data
|
||
|
|
o total amount of uploaded data
|
||
|
|
o number of transfers to perform
|
||
|
|
o number of concurrent transfers being transferred right now
|
||
|
|
o number of transfers queued up waiting to start
|
||
|
|
o total time all transfers are expected to take (if sizes are known)
|
||
|
|
o current time the transfers have spent so far
|
||
|
|
o estimated time left (if sizes are known)
|
||
|
|
o current transfer speed (the faster of upload/download speeds measured over
|
||
|
|
the last few seconds)
|
||
|
|
|
||
|
|
Example:
|
||
|
|
|
||
|
|
DL% UL% Dled Uled Xfers Live Qd Total Current Left Speed
|
||
|
|
72 -- 37.9G 0 101 30 23 0:00:55 0:00:34 0:00:22 2752M
|
||
|
|
|
||
|
|
## Behavior differences
|
||
|
|
|
||
|
|
Connections are shared fine between different easy handles, but the
|
||
|
|
"authentication contexts" are not. So for example doing HTTP Digest auth with
|
||
|
|
one handle for a particular transfer and then continue on with another handle
|
||
|
|
that reuses the same connection, the second handle cannot send the necessary
|
||
|
|
Authorization header at once since the context is only kept in the original
|
||
|
|
easy handle.
|
||
|
|
|
||
|
|
To fix this, the authorization state could be made possible to share with the
|
||
|
|
share API as well, as a context per origin + path (realm?) basically.
|
||
|
|
|
||
|
|
Visible in test 153, 1412 and more.
|