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new 0.3.0 | Mar 18, 2023 |
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0.2.8 | Feb 25, 2023 |
0.2.5 | Jan 28, 2023 |
0.1.11 | Nov 29, 2022 |
#51 in Asynchronous
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20KB
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rust-parallel
Command-line utility to execute commands in parallel and aggregate their output.
Similar interface to GNU Parallel or xargs but implemented in rust and tokio.
Always executes 1 process for each input line, similar to xargs -n1
or -L1
options.
Being written in asynchronous rust it is quite fast - see benchmarks.
Contents:
Usage:
$ rust-parallel --help
Execute commands in parallel
By Aaron Riekenberg <aaron.riekenberg@gmail.com>
https://github.com/aaronriekenberg/rust-parallel
https://crates.io/crates/rust-parallel
Usage: rust-parallel [OPTIONS] [COMMAND_AND_INITIAL_ARGUMENTS]...
Arguments:
[COMMAND_AND_INITIAL_ARGUMENTS]...
Optional command and initial arguments to run for each input line
Options:
-i, --input <INPUT>
Input file or - for stdin. Defaults to stdin if no inputs are specified
-j, --jobs <JOBS>
Maximum number of commands to run in parallel, defauts to num cpus
[default: 8]
-0, --null-separator
Use null separator for reading input instead of newline
-h, --help
Print help (see a summary with '-h')
-V, --version
Print version
Installation:
Recommended:
- Download a pre-built release from Github Releases.
- Extract the executable and put somewhere in your $PATH.
For manual installation/update:
- Install Rust
- Install the latest version of this app from crates.io:
$ cargo install rust-parallel
- The same
cargo install rust-parallel
command will also update to the latest version after initial installation.
Demos:
- Small demo of 5 echo commands. With
-j5
all 5 commands are run in parallel. With-j1
commands are run sequentially:
$ cat >./test <<EOL
echo hi
echo there
echo how
echo are
echo you
EOL
$ cat test | rust-parallel -j5
are
hi
there
how
you
$ cat test | rust-parallel -j1
hi
there
how
are
you
- Specifying command and intial arguments on command line:
$ head -100 /usr/share/dict/words | rust-parallel md5 -s
MD5 ("aal") = ff45e881572ca2c987460932660d320c
MD5 ("A") = 7fc56270e7a70fa81a5935b72eacbe29
MD5 ("aardvark") = 88571e5d5e13a4a60f82cea7802f6255
MD5 ("aalii") = 0a1ea2a8d75d02ae052f8222e36927a5
MD5 ("aam") = 35c2d90f7c06b623fe763d0a4e5b7ed9
MD5 ("aa") = 4124bc0a9335c27f086f24ba207a4912
MD5 ("a") = 0cc175b9c0f1b6a831c399e269772661
MD5 ("Aani") = e9b22dd6213c3d29648e8ad7a8642f2f
MD5 ("Aaron") = 1c0a11cc4ddc0dbd3fa4d77232a4e22e
MD5 ("aardwolf") = 66a4a1a2b442e8d218e8e99100069877
- Using
awk
to form complete commands:
$ head -100 /usr/share/dict/words | awk '{printf "md5 -s %s\n", $1}' | rust-parallel
MD5 ("Abba") = 5fa1e1f6e07a6fea3f2bb098e90a8de2
MD5 ("abaxial") = ac3a53971d52d9ce3277eadf03f13a5e
MD5 ("abaze") = 0b08c52aa63d947b6a5601ee975bc3a4
MD5 ("abaxile") = 21f5fc27d7d34117596e41d8c001087e
MD5 ("abbacomes") = 76640eb0c929bc97d016731bfbe9a4f8
MD5 ("abbacy") = 08aeac72800adc98d2aba540b6195921
MD5 ("Abbadide") = 7add1d6f008790fa6783bc8798d8c803
MD5 ("abb") = ea01e5fd8e4d8832825acdd20eac5104
- Using as part of a shell pipeline. stdout and stderr from each command run are copied to stdout/stderr of the rust-parallel process.
$ head -100 /usr/share/dict/words | rust-parallel md5 -s | grep -i abba
MD5 ("Abba") = 5fa1e1f6e07a6fea3f2bb098e90a8de2
MD5 ("abbacomes") = 76640eb0c929bc97d016731bfbe9a4f8
MD5 ("abbacy") = 08aeac72800adc98d2aba540b6195921
MD5 ("Abbadide") = 7add1d6f008790fa6783bc8798d8c803
- Working on a set of files from
find
command. The-0
option works nicely withfind -print0
to handle filenames with newline or whitespace characters:
$ mkdir testdir
$ touch 'testdir/a b' 'testdir/b c' 'testdir/c d'
$ find testdir -type f -print0 | rust-parallel -0 gzip -f -k
$ ls testdir
'a b' 'a b.gz' 'b c' 'b c.gz' 'c d' 'c d.gz'
- By default
rust-parallel
reads input from stdin only. The-i
option can be used 1 or more times to override this behavior.-i -
means read from stdin,-i ./test
means read from the file./test
:
$ cat >./test <<EOL
foo
bar
baz
EOL
$ head -5 /usr/share/dict/words | rust-parallel -i - -i ./test echo
A
aalii
aa
a
aal
bar
foo
baz
- Set environment variable
RUST_LOG=debug
to see debug output.
$ head -10 /usr/share/dict/words | RUST_LOG=debug rust-parallel md5 -s
Benchmarks:
See the wiki page for benchmarks.
Features:
- Use only safe rust.
- Use only asynchronous operations supported by tokio, do not use any blocking operations. This includes writing to stdout and stderr.
- Support arbitrarily large number of input lines, avoid
O(number of input lines)
memory usage. In support of this:tokio::sync::Semaphore
is used carefully to limit the number of commands that run concurrently. Do not spawn tasks for all input lines immediately to limit memory usage.
- Support running commands on local machine only, not on remote machines.
Tech Stack:
- anyhow used for application error handling to propogate and format fatal errors.
- clap command line argument parser.
- tokio asynchronous runtime for rust. From tokio this app uses:
async
/await
functions (aka coroutines)- Singleton
CommandLineArgs
instance usingtokio::sync::OnceCell
. - Asynchronous command execution using
tokio::process::Command
tokio::sync::Semaphore
used to limit number of commands that run concurrently.- Life would be a bit easier if
acquire_many
took ausize
parameter: https://github.com/tokio-rs/tokio/issues/4446
- Life would be a bit easier if
tokio::sync::Mutex
used to protect access to stdout/stderr to prevent interleaved command output.
- tracing structured debug and warning logs.
tracing::Instrument
is used to provide structured debug logs on methods incommand::Command
andcommand::CommandService
.
Dependencies
~5–10MB
~163K SLoC