getline is much slower when reading from a pipe or redirected file compared with mawk.

[ghuls]

As frawk development has stalled for the moment, you might have some time to investigate the relative slowness of getline when reading from a pipe (eg. "cat - " | or a redirected file (e.g < "/dev/stdin").

ezrosent#98 (comment)

Also zawk is slower than frawk (but this might be due the fact that I didn't manage to build it with unstable feature yet.

# Read and print all input lines.
$ time yes | head -n 100000000 | mawk '{ print $0 }' > /dev/null

real    0m4.562s
user    0m4.472s
sys     0m0.300s

$ time yes | head -n 100000000 | frawk '{ print $0 }' > /dev/null

real    0m8.485s
user    0m8.544s
sys     0m0.292s

$ time yes | head -n 100000000 | /software/zawk/target/release/zawk '{ print $0 }' > /dev/null                                                                  

real    0m13.969s
user    0m14.031s
sys     0m0.291s


$ time yes | head -n 100000000 | mawk 'BEGIN { while ( (getline ) > 0 ) { print $0 } }' > /dev/null

real    0m7.293s
user    0m7.143s
sys     0m0.309s

$ time yes | head -n 100000000 | frawk 'BEGIN { while ( (getline ) > 0 ) { print $0 } }' > /dev/null

real    0m7.279s
user    0m7.351s
sys     0m0.288s

$ time yes | head -n 100000000 | /software/zawk/target/release/zawk 'BEGIN { while ( (getline ) > 0 ) { print $0 } }' > /dev/null                               

real    0m11.796s
user    0m11.818s
sys     0m0.311s


# Count number of input lines:
$ time yes | head -n 100000000 | mawk 'END { print NR }'
100000000

real    0m2.245s
user    0m2.141s
sys     0m0.276s

$ time yes | head -n 100000000 | frawk 'END { print NR }'
100000000

real    0m3.905s
user    0m3.963s
sys     0m0.272s

$ time yes | head -n 100000000 | /software/zawk/target/release/zawk 'END { print NR }'                                                                          
100000000

real    0m6.300s
user    0m6.328s
sys     0m0.295s


$ time yes | head -n 100000000 | mawk 'BEGIN { while ( (getline ) > 0 ) { line_count += 1;} print line_count}'
100000000

real    0m5.724s
user    0m5.619s
sys     0m0.290s

$ time yes | head -n 100000000 | frawk 'BEGIN { while ( (getline ) > 0 ) { line_count += 1;} print line_count}'
100000000

real    0m2.628s
user    0m2.686s
sys     0m0.267s

$ time yes | head -n 100000000 | /software/zawk/target/release/zawk 'BEGIN { while ( (getline ) > 0 ) { line_count += 1;} print line_count}'                    
100000000

real    0m4.128s
user    0m4.186s
sys     0m0.265s


$ time yes | head -n 100000000 | mawk 'BEGIN { while ( (getline < "/dev/stdin") > 0 ) { line_count += 1;} print line_count}'       
100000000

real    0m6.523s
user    0m6.440s
sys     0m0.265s

$ time yes | head -n 100000000 | frawk 'BEGIN { while ( (getline < "/dev/stdin") > 0 ) { line_count += 1;} print line_count}'                                                                      
100000000

real    0m20.624s
user    0m20.635s
sys     0m0.300s

$ time yes | head -n 100000000 | /software/zawk/target/release/zawk 'BEGIN { while ( (getline < "/dev/stdin") > 0 ) { line_count += 1;} print line_count}'      
100000000

real    0m29.226s
user    0m29.207s
sys     0m0.300s


$ time yes | head -n 100000000 | mawk 'BEGIN { while ( ("cat -" | getline) > 0 ) { line_count += 1;} print line_count}'            
100000000

real    0m6.426s
user    0m6.367s
sys     0m0.384s

$ time yes | head -n 100000000 | frawk 'BEGIN { while ( ("cat -" | getline) > 0 ) { line_count += 1;} print line_count}'                                                                          
100000000

real    0m20.072s
user    0m20.063s
sys     0m0.369s

$ time yes | head -n 100000000 | /software/zawk/target/release/zawk 'BEGIN { while ( ("cat -" | getline) > 0 ) { line_count += 1;} print line_count}'           
100000000

real    0m28.472s
user    0m28.406s
sys     0m0.416s