Shell命令使用pipe道时速度较慢,中间文件速度较快

有没有人了解这种处理时间,使用中间文件或使用pipe道时的巨大差异? 我使用新鲜的debian挤压服务器上的标准工具将tiff转换为pdf。 一个标准的做法是首先转换为ps。

无pipe道:

root@web5:~# time tiff2ps test.tif > test.ps real 0m0.860s user 0m0.744s sys 0m0.112s root@web5:~# time ps2pdf13 -sPAPERSIZE=a4 test.ps > test.pdf real 0m0.667s user 0m0.612s sys 0m0.060s 

用pipe道:

 root@web5:~# time tiff2ps test.tif | ps2pdf13 -sPAPERSIZE=a4 - > test.pdf real 1m6.098s user 0m15.861s sys 0m50.9 

在最后一个命令中,gs进程始终处于100%。

更新
这是ps世代的strace输出:

 root@web5:~# strace tiff2ps test.tif > test.ps execve("/usr/bin/tiff2ps", ["tiff2ps", "test.tif"], [/* 28 vars */]) = 0 brk(0) = 0x1395000 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a1937000 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory) open("/etc/ld.so.cache", O_RDONLY) = 3 fstat(3, {st_mode=S_IFREG|0644, st_size=21735, ...}) = 0 mmap(NULL, 21735, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fb5a1931000 close(3) = 0 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) open("/usr/lib/libtiff.so.4", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0P\200\0\0\0\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0644, st_size=405128, ...}) = 0 mmap(NULL, 2501416, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fb5a14b9000 mprotect(0x7fb5a151a000, 2093056, PROT_NONE) = 0 mmap(0x7fb5a1719000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x60000) = 0x7fb5a1719000 close(3) = 0 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) open("/usr/lib/libjpeg.so.62", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\3408\0\0\0\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0644, st_size=145048, ...}) = 0 mmap(NULL, 2240080, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fb5a1296000 mprotect(0x7fb5a12b9000, 2093056, PROT_NONE) = 0 mmap(0x7fb5a14b8000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x22000) = 0x7fb5a14b8000 close(3) = 0 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) open("/usr/lib/libz.so.1", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\260\"\0\0\0\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0644, st_size=93936, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a1930000 mmap(NULL, 2188976, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fb5a107f000 mprotect(0x7fb5a1096000, 2093056, PROT_NONE) = 0 mmap(0x7fb5a1295000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x16000) = 0x7fb5a1295000 close(3) = 0 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) open("/lib/libm.so.6", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\360>\0\0\0\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0644, st_size=530736, ...}) = 0 mmap(NULL, 2625768, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fb5a0dfd000 mprotect(0x7fb5a0e7d000, 2097152, PROT_NONE) = 0 mmap(0x7fb5a107d000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x80000) = 0x7fb5a107d000 close(3) = 0 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) open("/lib/libc.so.6", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\240\355\1\0\0\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0755, st_size=1437064, ...}) = 0 mmap(NULL, 3545160, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fb5a0a9b000 mprotect(0x7fb5a0bf4000, 2093056, PROT_NONE) = 0 mmap(0x7fb5a0df3000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x158000) = 0x7fb5a0df3000 mmap(0x7fb5a0df8000, 18504, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fb5a0df8000 close(3) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a192f000 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a192e000 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a192d000 arch_prctl(ARCH_SET_FS, 0x7fb5a192e700) = 0 mprotect(0x7fb5a0df3000, 16384, PROT_READ) = 0 mprotect(0x7fb5a107d000, 4096, PROT_READ) = 0 mprotect(0x7fb5a1939000, 4096, PROT_READ) = 0 munmap(0x7fb5a1931000, 21735) = 0 open("test.tif", O_RDONLY) = 3 brk(0) = 0x1395000 brk(0x13b6000) = 0x13b6000 read(3, "II*\0\10\0\0\0", 8) = 8 fstat(3, {st_mode=S_IFREG|0644, st_size=1825656, ...}) = 0 mmap(NULL, 1825656, PROT_READ, MAP_SHARED, 3, 0) = 0x7fb5a176f000 open("/proc/meminfo", O_RDONLY) = 4 fstat(4, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a1936000 read(4, "MemTotal: 2090844 kB\nMemF"..., 1024) = 1024 close(4) = 0 munmap(0x7fb5a1936000, 4096) = 0 write(2, "TIFFReadDirectory: ", 19TIFFReadDirectory: ) = 19 write(2, "Warning, ", 9Warning, ) = 9 write(2, "test.tif: wrong data type 7 for "..., 59test.tif: wrong data type 7 for "RichTIFFIPTC"; tag ignored) = 59 write(2, ".\n", 2. ) = 2 gettimeofday({1334836895, 374666}, NULL) = 0 fstat(1, {st_mode=S_IFREG|0664, st_size=0, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a1936000 open("/etc/localtime", O_RDONLY) = 4 fstat(4, {st_mode=S_IFREG|0644, st_size=1892, ...}) = 0 fstat(4, {st_mode=S_IFREG|0644, st_size=1892, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb5a1935000 read(4, "TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\4\0\0\0\4\0\0\0\0"..., 4096) = 1892 lseek(4, -1217, SEEK_CUR) = 675 read(4, "TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\6\0\0\0\6\0\0\0\0"..., 4096) = 1217 close(4) = 0 munmap(0x7fb5a1935000, 4096) = 0 write(1, "%!PS-Adobe-3.0 EPSF-3.0\n%%Creato"..., 4096) = 4096 write(1, "fffffffffffffffffffffffffffff\nff"..., 4096) = 4096 write(1, "ffffffffffffffffffff\nfffffffffff"..., 4096) = 4096 write(1, "fffffffffff\nffffffffffffffffffff"..., 4096) = 4096 write(1, "ff\nfffffffffffffffffffffffffffff"..., 4096) = 4096 write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096 write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096 write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096 write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096 write(1, "ffffffffffffffffffffffff\nfffffff"..., 4096) = 4096 

下面是pipe道版本的strace输出:输出到ps2pdf13时,PS的生成似乎要慢很多。

 root@web5:~# strace tiff2ps test.tif | ps2pdf13 -sPAPERSIZE=a4 - > test.pdf execve("/usr/bin/tiff2ps", ["tiff2ps", "test.tif"], [/* 28 vars */]) = 0 brk(0) = 0x1b97000 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208bb1000 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory) open("/etc/ld.so.cache", O_RDONLY) = 3 fstat(3, {st_mode=S_IFREG|0644, st_size=21735, ...}) = 0 mmap(NULL, 21735, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f9208bab000 close(3) = 0 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) open("/usr/lib/libtiff.so.4", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0P\200\0\0\0\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0644, st_size=405128, ...}) = 0 mmap(NULL, 2501416, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f9208733000 mprotect(0x7f9208794000, 2093056, PROT_NONE) = 0 mmap(0x7f9208993000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x60000) = 0x7f9208993000 close(3) = 0 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) open("/usr/lib/libjpeg.so.62", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\3408\0\0\0\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0644, st_size=145048, ...}) = 0 mmap(NULL, 2240080, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f9208510000 mprotect(0x7f9208533000, 2093056, PROT_NONE) = 0 mmap(0x7f9208732000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x22000) = 0x7f9208732000 close(3) = 0 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) open("/usr/lib/libz.so.1", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\260\"\0\0\0\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0644, st_size=93936, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208baa000 mmap(NULL, 2188976, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f92082f9000 mprotect(0x7f9208310000, 2093056, PROT_NONE) = 0 mmap(0x7f920850f000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x16000) = 0x7f920850f000 close(3) = 0 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) open("/lib/libm.so.6", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\360>\0\0\0\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0644, st_size=530736, ...}) = 0 mmap(NULL, 2625768, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f9208077000 mprotect(0x7f92080f7000, 2097152, PROT_NONE) = 0 mmap(0x7f92082f7000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x80000) = 0x7f92082f7000 close(3) = 0 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) open("/lib/libc.so.6", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\240\355\1\0\0\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0755, st_size=1437064, ...}) = 0 mmap(NULL, 3545160, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f9207d15000 mprotect(0x7f9207e6e000, 2093056, PROT_NONE) = 0 mmap(0x7f920806d000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x158000) = 0x7f920806d000 mmap(0x7f9208072000, 18504, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f9208072000 close(3) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208ba9000 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208ba8000 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208ba7000 arch_prctl(ARCH_SET_FS, 0x7f9208ba8700) = 0 mprotect(0x7f920806d000, 16384, PROT_READ) = 0 mprotect(0x7f92082f7000, 4096, PROT_READ) = 0 mprotect(0x7f9208bb3000, 4096, PROT_READ) = 0 munmap(0x7f9208bab000, 21735) = 0 open("test.tif", O_RDONLY) = 3 brk(0) = 0x1b97000 brk(0x1bb8000) = 0x1bb8000 read(3, "II*\0\10\0\0\0", 8) = 8 fstat(3, {st_mode=S_IFREG|0644, st_size=1825656, ...}) = 0 mmap(NULL, 1825656, PROT_READ, MAP_SHARED, 3, 0) = 0x7f92089e9000 open("/proc/meminfo", O_RDONLY) = 4 fstat(4, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208bb0000 read(4, "MemTotal: 2090844 kB\nMemF"..., 1024) = 1024 close(4) = 0 munmap(0x7f9208bb0000, 4096) = 0 write(2, "TIFFReadDirectory: ", 19TIFFReadDirectory: ) = 19 write(2, "Warning, ", 9Warning, ) = 9 write(2, "test.tif: wrong data type 7 for "..., 59test.tif: wrong data type 7 for "RichTIFFIPTC"; tag ignored) = 59 write(2, ".\n", 2. ) = 2 gettimeofday({1334836513, 114140}, NULL) = 0 fstat(1, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208bb0000 open("/etc/localtime", O_RDONLY) = 4 fstat(4, {st_mode=S_IFREG|0644, st_size=1892, ...}) = 0 fstat(4, {st_mode=S_IFREG|0644, st_size=1892, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f9208baf000 read(4, "TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\4\0\0\0\4\0\0\0\0"..., 4096) = 1892 lseek(4, -1217, SEEK_CUR) = 675 read(4, "TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\6\0\0\0\6\0\0\0\0"..., 4096) = 1217 close(4) = 0 munmap(0x7f9208baf000, 4096) = 0 write(1, "%!PS-Adobe-3.0 EPSF-3.0\n%%Creato"..., 4096) = 4096 write(1, "fffffffffffffffffffffffffffff\nff"..., 4096) = 4096 write(1, "ffffffffffffffffffff\nfffffffffff"..., 4096) = 4096 write(1, "fffffffffff\nffffffffffffffffffff"..., 4096) = 4096 write(1, "ff\nfffffffffffffffffffffffffffff"..., 4096) = 4096 write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096 write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096 write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096 write(1, "ffffffffffffffffffffffffffffffff"..., 4096) = 4096 ...etc... 

编辑:我运行在您的源文件在我的环境中,并有以下结果:

 [root@xt ~]# time tiff2ps test.tif > test.ps real 0m0.795s user 0m0.659s sys 0m0.135s [root@xt ~]# time ps2pdf13 -sPAPERSIZE=a4 test.ps > test.pdf real 0m0.592s user 0m0.513s sys 0m0.075s [root@xt ~]# time tiff2ps test.tif | ps2pdf13 -sPAPERSIZE=a4 - > test2.pdf real 0m13.110s user 0m4.601s sys 0m7.260s 

我添加了pv命令来查看发生了什么。 这是发生了什么事情:

 [root@xt ~]# time tiff2ps test.tif | pv | ps2pdf13 -sPAPERSIZE=a4 - > test2.pdf 50.5MB 0:00:12 [4.05MB/s] [ <=> ] real 0m13.934s user 0m4.751s sys 0m8.261s 

将50兆字节的Postscript输出传送到ps2pdf13命令! @janneb是正确的,这是一个缓冲/pipe道问题。 我试图利用unbuffer命令 ,但Ghostscript不喜欢伪terminal。

有什么理由不能使用tiff2pdf命令吗?

 [root@xt ~]# time tiff2pdf -o test2.pdf test.tif real 0m0.242s user 0m0.176s sys 0m0.064s