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48 lines
1.5 KiB
C++
48 lines
1.5 KiB
C++
/**
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g++ pipe_fds.cpp -g -O0 -o pipe_fds
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About the limits:
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[winlin@dev6 srs]$ ulimit -n
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1024
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[winlin@dev6 srs]$ sudo lsof -p 21182
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pipe_fds 21182 winlin 0u CHR 136,4 0t0 7 /dev/pts/4
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pipe_fds 21182 winlin 1u CHR 136,4 0t0 7 /dev/pts/4
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pipe_fds 21182 winlin 2u CHR 136,4 0t0 7 /dev/pts/4
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pipe_fds 21182 winlin 3r FIFO 0,8 0t0 464543 pipe
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pipe_fds 21182 winlin 1021r FIFO 0,8 0t0 465052 pipe
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pipe_fds 21182 winlin 1022w FIFO 0,8 0t0 465052 pipe
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So, all fds can be open is <1024, that is, can open 1023 files.
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The 0, 1, 2 is opened file, so can open 1023-3=1020files,
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Where 1020/2=512, so we can open 512 pipes.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <errno.h>
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#include <string.h>
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int main(int argc, char** argv)
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{
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if (argc <= 1) {
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printf("Usage: %s <nb_pipes>\n"
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" nb_pipes the pipes to open.\n"
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"For example:\n"
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" %s 1024\n", argv[0], argv[0]);
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exit(-1);
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}
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int nb_pipes = ::atoi(argv[1]);
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for (int i = 0; i < nb_pipes; i++) {
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int fds[2];
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if (pipe(fds) < 0) {
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printf("failed to create pipe. i=%d, errno=%d(%s)\n",
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i, errno, strerror(errno));
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break;
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}
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}
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printf("Press CTRL+C to quit, use bellow command to show the fds opened:\n");
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printf(" sudo lsof -p %d\n", getpid());
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sleep(-1);
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return 0;
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}
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