<meta http-equiv="Content-Type" content="text/html; charset=gb2312"><div style="line-height:1.7;color:#000000;font-size:14px;font-family:Arial"><div>Hi.</div><div>The following server/client example is selected from OpenMPI. </div><div>I compile and run the example by using OpenMPI, everything is OK.</div><div>BUT, I compile and run it by mpich(3.1.3), which is BLOCKED as my example!</div><div><br></div><div>This is a bug?</div><div><div><br></div><div>#include <stdio.h></div><div>#include <stdlib.h></div><div>#include <string.h></div><div>#include <errno.h></div><div>#include <unistd.h></div><div>#include <mpi.h></div><div><br></div><div>/*</div><div><br></div><div> LOGIC:</div><div><br></div><div> - the 'server' opens a port and write the info to a file</div><div> - the 'clients' open the file and connect to the port</div><div> - after each accept, the server and client do a merge to</div><div> convert the intercomm to an intracomm</div><div><br></div><div> DETAIL STEPS:</div><div><br></div><div> - server open port</div><div> - server does accept</div><div> - client #1 does connect</div><div> - server and client #1 do merge</div><div> - server does accept</div><div> - client #2 does connect</div><div> - server, client #1 and client #2 do merge</div><div> - server does accept</div><div> - client #3 does connect</div><div> - server, client #1, client #2 and client #3 do merge</div><div><br></div><div>*/</div><div><br></div><div>#define TAG 0</div><div><br></div><div>#define CHK(code) do \</div><div> { \</div><div> int retval = code ; \</div><div> if (retval != MPI_SUCCESS) \</div><div> { \</div><div> fprintf(stderr, "Error: " #code "\n") ; \</div><div> exit(1) ; \</div><div> } \</div><div> } while(0)</div><div><br></div><div>int main(int argc, char *argv[])</div><div>{</div><div> char hostname[255] ;</div><div> char buff[255] ;</div><div><br></div><div> int role ;</div><div> int num_clients ;</div><div> int size, rank ;</div><div><br></div><div> FILE *fp ;</div><div> char server_port_name[MPI_MAX_PORT_NAME] ;</div><div><br></div><div> MPI_Comm intercomm, intracomm ;</div><div> MPI_Status status ;</div><div> int msg_count ;</div><div> int i ;</div><div><br></div><div> /* sanity check the args */</div><div> if(argc != 3)</div><div> {</div><div> fprintf(stderr, "usage %s <num clients> <1:server | 0:client>\n", argv[0]) ;</div><div> exit(1) ;</div><div> }</div><div><br></div><div> num_clients = atoi(argv[1]) ;</div><div> role = atoi(argv[2]) ;</div><div><br></div><div> if (num_clients <= 0 || (role != 0 && role != 1))</div><div> {</div><div> fprintf(stderr, "usage %s <num clients> <1:server | 0:client>\n", argv[0]) ;</div><div> exit(1) ;</div><div> }</div><div><br></div><div> /* initialize MPI */</div><div> CHK(MPI_Init(&argc, &argv)) ;</div><div><br></div><div> /* get the node name */</div><div> {</div><div> int retval = gethostname(hostname, 255) ;</div><div> if(retval == -1)</div><div> {</div><div> fprintf(stderr, "gethostname failed: %s\n", strerror(errno)) ;</div><div> exit(1) ;</div><div> }</div><div> }</div><div><br></div><div> /* server */</div><div> if(role == 1)</div><div> {</div><div> printf("SERVER: on node '%s'\n", hostname) ;</div><div><br></div><div> /* open port to establish connections */</div><div> CHK(MPI_Open_port(MPI_INFO_NULL, server_port_name)) ;</div><div><br></div><div> printf("SERVER: opened port=%s\n", server_port_name) ;</div><div><br></div><div> /* store the port name */</div><div> fp = fopen("server_port_name.txt", "w") ;</div><div> if(fp == NULL)</div><div> {</div><div> fprintf(stderr, "fopen failed: %s\n", strerror(errno)) ;</div><div> exit(1) ;</div><div> }</div><div> fprintf(fp, "%s", server_port_name) ;</div><div> fclose(fp) ;</div><div><br></div><div> /* the server accepts connections from all the clients */</div><div> for(i = 0 ; i < num_clients ; i++ )</div><div> {</div><div> /* accept connections at this port */</div><div> CHK(MPI_Comm_accept(server_port_name, MPI_INFO_NULL, 0,</div><div> i == 0 ? MPI_COMM_WORLD : intracomm,</div><div> &intercomm)) ;</div><div><br></div><div> printf("SERVER: accepted connection from client %d\n", i+1) ;</div><div><br></div><div> /* merge, to form one intra communicator */</div><div> CHK(MPI_Intercomm_merge(intercomm, 0, &intracomm)) ;</div><div><br></div><div> printf("SERVER: merged with client %d\n", i+1) ;</div><div><br></div><div> CHK(MPI_Comm_size(intracomm, &size)) ;</div><div> CHK(MPI_Comm_rank(intracomm, &rank)) ;</div><div><br></div><div> printf("SERVER: after merging with client %d: size=%d rank=%d\n", i+1, size, rank) ;</div><div> }</div><div> } /* end server */</div><div><br></div><div> /* client */</div><div> if(role == 0)</div><div> {</div><div> printf("CLIENT: on node '%s'\n", hostname) ;</div><div><br></div><div> fp = fopen("server_port_name.txt", "r") ;</div><div> if(fp == NULL)</div><div> {</div><div> fprintf(stderr, "fopen failed: %s\n", strerror(errno)) ;</div><div> exit(1) ;</div><div> }</div><div> fscanf(fp, "%s", server_port_name) ;</div><div> fclose(fp) ;</div><div><br></div><div> printf("CLIENT: attempting to connect to server on port=%s\n", server_port_name) ;</div><div><br></div><div> /* connect to the server */</div><div> CHK(MPI_Comm_connect (server_port_name, MPI_INFO_NULL, 0, MPI_COMM_WORLD, &intercomm)) ;</div><div><br></div><div> printf("CLIENT: connected to server on port\n") ;</div><div><br></div><div> /* merge the server and client to one intra communicator */</div><div> CHK(MPI_Intercomm_merge(intercomm, 1, &intracomm)) ;</div><div><br></div><div> printf("CLIENT: merged with existing intracomm\n") ;</div><div><br></div><div> CHK(MPI_Comm_size(intracomm, &size)) ;</div><div> CHK(MPI_Comm_rank(intracomm, &rank)) ;</div><div><br></div><div> printf("CLIENT: after merging, new comm: size=%d rank=%d\n", size, rank) ;</div><div><br></div><div> for (i = rank ; i < num_clients ; i++)</div><div> {</div><div> /* client performs a collective accept */</div><div> CHK(MPI_Comm_accept(server_port_name, MPI_INFO_NULL, 0, intracomm, &intercomm)) ;</div><div><br></div><div> printf("CLIENT: connected to server on port\n") ;</div><div><br></div><div> /* merge the two intra comms back to one communicator */</div><div> CHK(MPI_Intercomm_merge(intercomm, 0, &intracomm)) ;</div><div><br></div><div> printf("CLIENT: merged with existing members\n") ;</div><div><br></div><div> CHK(MPI_Comm_size(intracomm, &size)) ;</div><div> CHK(MPI_Comm_rank(intracomm, &rank)) ;</div><div><br></div><div> printf("CLIENT: new size after merging with existing members: size=%d rank=%d\n", size, rank) ;</div><div> }</div><div><br></div><div> } /* end client */</div><div><br></div><div> CHK(MPI_Comm_size(intracomm, &size)) ;</div><div> CHK(MPI_Comm_rank(intracomm, &rank)) ;</div><div><br></div><div> printf("After fusion: size=%d rank=%d\n", size, rank) ;</div><div><br></div><div> if(rank == 0)</div><div> {</div><div> msg_count = num_clients ;</div><div><br></div><div> while(msg_count)</div><div> {</div><div> CHK(MPI_Recv(buff, 255, MPI_CHAR, MPI_ANY_SOURCE,</div><div> MPI_ANY_TAG, intracomm, &status)) ;</div><div><br></div><div> printf("Received hello msg from '%s'\n", buff) ;</div><div> msg_count-- ;</div><div> }</div><div> }</div><div> else</div><div> {</div><div> /* all ranks > 0 */</div><div><br></div><div> CHK(MPI_Send(hostname, strlen(hostname) + 1, MPI_CHAR, 0, TAG, intracomm)) ;</div><div> }</div><div><br></div><div> CHK(MPI_Finalize()) ;</div><div><br></div><div> fprintf(stderr, "Rank %d is exiting\n", rank);</div><div> return 0 ;</div><div>}</div></div><br><div></div><div id="divNeteaseMailCard"></div><br>At 2015-01-24 10:43:07, "haozi" <yidanyiji@163.com> wrote:<br> <blockquote id="isReplyContent" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid"><div style="line-height:1.7;color:#000000;font-size:14px;font-family:Arial"><div>Thanks, Bland and Lu.</div><div><br></div><div>You are right.</div><div>These functions (such as MPI_Comm_accept, MPI_Comm_connect, MPI_Intercomm_merge) can help me to get a new<span style="line-height: 23.7999992370605px;"> </span><span style="line-height: 23.7999992370605px;">intra-communicator which </span>contains ALL MPI processes.</div><div><br></div><div>Now, I have a more complicated example:</div><div> I have a server and a client. </div><div> After they merge into an <span style="line-height: 23.7999992370605px;">intra-communicator by using connect/accept/merge fucntions, another client would plant to join them, too.</span></div><div><span style="line-height: 23.7999992370605px;"> I thought that the code is simular, but the code CAN'T work: Second client CAN'T connect. The new comm CAN'T accept. They all BLOCK.</span></div><div><div style="line-height: 23.7999992370605px;"><br class="Apple-interchange-newline"> As you see, the second client BLOCKs at <span style="line-height: 23.7999992370605px;">MPI_Comm_connect, and processes of newcomm BLOCK at </span><span style="line-height: 23.7999992370605px;">MPI_Comm_accept.</span></div><div style="line-height: 23.7999992370605px;"><span style="line-height: 23.7999992370605px;"> What's Wrong with my code? </span></div></div><div style="line-height: 23.7999992370605px;"><span style="line-height: 23.7999992370605px;"><br></span></div><div>//server</div><div><div>#include "mpi.h"</div><div>int main(int argc, char *argv[])</div><div>{</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Comm client, client2, newcomm, newcomm2;</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Status status;</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>char port_name[MPI_MAX_PORT_NAME];</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>char port_name2[MPI_MAX_PORT_NAME];</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>int size, again, rank, myrank;</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Init(&argc, &argv);</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Open_port(MPI_INFO_NULL, port_name);<span style="line-height: 23.7999992370605px;">//OK</span></div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Comm_accept(port_name, MPI_INFO_NULL, 0, MPI_COMM_WORLD,&client);<span style="line-height: 23.7999992370605px;">//OK</span></div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Intercomm_merge(client,11,&newcomm);//OK</div><div><br></div><div> <span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Barrier(newcomm);//OK</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Open_port(MPI_INFO_NULL, port_name2);// OK</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Comm_accept(port_name2, MPI_INFO_NULL, 0, newcomm,&client2);// BLOCK here, Wath's wrong?</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Intercomm_merge(client2,12,&newcomm2);</div><div><br></div><div> <span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Barrier(newcomm2);</div><div><br></div><div> <span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Close_port(port_name);</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Comm_disconnect(&client);</div><div> <span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Close_port(port_name2);</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Comm_disconnect(&client2);</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Finalize();</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>return 0;</div><div>}</div></div><div><br></div><div>//first client</div><div><div>#include "mpi.h"</div><div><span style="line-height: 1.7;">int main( int argc, char **argv )</span></div><div>{</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Comm server,newcomm,newcomm2,client2;</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>char port_name[MPI_MAX_PORT_NAME];</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>char port_name2[MPI_MAX_PORT_NAME];</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>int size,rank;</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Init( &argc, &argv );</div><div><span class="Apple-tab-span" style="white-space:pre"> </span></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>strcpy( port_name, argv[1] );</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Comm_connect( port_name, MPI_INFO_NULL, 0, MPI_COMM_SELF,&server );<span style="line-height: 23.7999992370605px;">//OK</span></div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Intercomm_merge(server,11,&newcomm);//OK</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Barrier(newcomm);//OK</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Open_port(MPI_INFO_NULL, port_name2);//OK</div><div><span class="Apple-tab-span" style="white-space:pre"> </span></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Comm_accept(port_name2, MPI_INFO_NULL, 0, newcomm,&client2);<span style="line-height: 23.7999992370605px;">// BLOCK here, Wath's wrong?</span></div><div><span style="line-height: 23.7999992370605px;"><br></span></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Intercomm_merge(client2,12,&newcomm2);</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Barrier(newcomm2);</div><div><br></div><div> <span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Close_port(port_name2);</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Comm_disconnect(&client2);</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Comm_disconnect( &server );</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Finalize();</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>return 0;</div><div>}</div><div><br></div></div><div>//second client</div><div><div>#include "mpi.h"</div><div>int main( int argc, char **argv )</div><div>{</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Comm server,newcomm;</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>char port_name[MPI_MAX_PORT_NAME];</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>int size,rank;</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Init( &argc, &argv );</div><div><span class="Apple-tab-span" style="white-space:pre"> </span></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>strcpy( port_name, argv[1] );//OK</div><div><span class="Apple-tab-span" style="line-height: 1.7; white-space: pre;"> </span></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Comm_connect( port_name, MPI_INFO_NULL, 0, MPI_COMM_SELF,&server );<span style="line-height: 23.7999992370605px;">// BLOCK here, Wath's wrong?</span></div><div><span class="Apple-tab-span" style="white-space:pre"> </span></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Comm_size(MPI_COMM_WORLD, &size);</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Intercomm_merge(server,11,&newcomm);</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Barrier(newcomm);</div><div><span class="Apple-tab-span" style="white-space:pre"> </span></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Comm_disconnect( &server );</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>MPI_Finalize();</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>return 0;</div><div>}</div><div><br></div></div><div><br></div><br><div></div><div></div><br>At 2015-01-23 23:14:06, "Wesley Bland" <<a href="mailto:wbland@anl.gov">wbland@anl.gov</a>> wrote:<br> <blockquote id="isReplyContent" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid"><div dir="ltr"><div class="markdown-here-wrapper" style=""><p style="margin:1.2em 0px!important">The size of <code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;padding:0px 0.3em;white-space:pre-wrap;border:1px solid rgb(234,234,234);background-color:rgb(248,248,248);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;display:inline">MPI_COMM_WORLD</code> will never change. That communicator is set at initialization time and is not ever modified. However, when you finish connect/accept, you get a new communicator which you can merge into an intra-communicator which functions exactly like <code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;padding:0px 0.3em;white-space:pre-wrap;border:1px solid rgb(234,234,234);background-color:rgb(248,248,248);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;display:inline">MPI_COMM_WORLD</code>. Don¡¯t be attached to the variable name <code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;padding:0px 0.3em;white-space:pre-wrap;border:1px solid rgb(234,234,234);background-color:rgb(248,248,248);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;display:inline">MPI_COMM_WORLD</code>. It¡¯s just a variable and you can use a different one with very little extra work.</p>
<p style="margin:1.2em 0px!important">Thanks,<br>Wesley</p>
<div title="MDH:VGhlIHNpemUgb2YgYE1QSV9DT01NX1dPUkxEYCB3aWxsIG5ldmVyIGNoYW5nZS4gVGhhdCBjb21t
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ZGl2Pldlc2xleTwvZGl2Pg==" style="height:0;font-size:0em;padding:0;margin:0"></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Jan 22, 2015 at 6:14 PM, haozi <span dir="ltr"><<a href="mailto:yidanyiji@163.com" target="_blank">yidanyiji@163.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>
<div style="line-height:1.7;color:#000000;font-size:14px;font-family:Arial">
<div>Thanks, Lu.</div>
<div>My simple code is as following.</div>
<div>//server</div>
<div>
<div>#include "mpi.h"</div>
<div><br>
</div>
<div>int main(int argc, char *argv[])</div>
<div>{</div>
<div><span style="white-space:pre-wrap"></span>MPI_Comm client;</div>
<div><span style="white-space:pre-wrap"></span>MPI_Status status;</div>
<div><span style="white-space:pre-wrap"></span>char port_name[MPI_MAX_PORT_NAME];</div>
<div><span style="white-space:pre-wrap"></span>int size, again;</div>
<div><br>
</div>
<div><span style="white-space:pre-wrap"></span>MPI_Init(&argc, &argv);</div>
<div><span style="white-space:pre-wrap"></span>MPI_Comm_size(MPI_COMM_WORLD, &size);</div>
<div><span style="white-space:pre-wrap"></span>MPI_Open_port(MPI_INFO_NULL, port_name);</div>
<div><span style="white-space:pre-wrap"></span>printf("server port_name is %s\n\n", port_name);</div>
<div><span style="white-space:pre-wrap"></span>MPI_Comm_accept(port_name, MPI_INFO_NULL, 0, MPI_COMM_WORLD,&client);</div>
<div><span style="white-space:pre-wrap"></span>MPI_Comm_size(MPI_COMM_WORLD, &size);</div>
<div><span style="white-space:pre-wrap"></span>printf("At server, comm_size=%d @ MPI_COMM_WORLD=%x, Client_World=%x\n",size,MPI_COMM_WORLD, client);</div>
<div><span style="white-space:pre-wrap"></span>MPI_Comm_size(client, &size);</div>
<div><span style="white-space:pre-wrap"></span>printf("At server, client_size=%d @ MPI_COMM_WORLD=%x, Client_World=%x\n",size,MPI_COMM_WORLD, client);</div>
<div><br>
</div>
<div><span style="white-space:pre-wrap"></span>MPI_Comm_disconnect(&client);</div>
<div><span style="white-space:pre-wrap"></span>MPI_Finalize();</div>
<div><span style="white-space:pre-wrap"></span>return 0;</div>
<div>}</div>
</div>
<br>
<div>//client</div>
<div>
<div>#include "mpi.h"</div>
<div><br>
</div>
<div>int main( int argc, char **argv )</div>
<div>{</div>
<div><span style="white-space:pre-wrap"></span>MPI_Comm server;</div>
<div><span style="white-space:pre-wrap"></span>char port_name[MPI_MAX_PORT_NAME];</div>
<div><span style="white-space:pre-wrap"></span>int size;</div>
<div><br>
</div>
<div><span style="white-space:pre-wrap"></span>MPI_Init( &argc, &argv );</div>
<div><span style="white-space:pre-wrap"></span>strcpy( port_name, argv[1] );</div>
<div><span style="white-space:pre-wrap"></span>printf("server port name:%s\n",port_name);</div>
<div><span style="white-space:pre-wrap"></span>MPI_Comm_connect( port_name, MPI_INFO_NULL, 0, MPI_COMM_WORLD,&server );</div>
<div><span style="white-space:pre-wrap"></span>MPI_Comm_size(MPI_COMM_WORLD, &size);</div>
<div><span style="white-space:pre-wrap"></span>printf("At client, comm_size=%d @ MPI_COMM_WORLD=%x, Server_World=%x\n",size,MPI_COMM_WORLD,server);</div>
<div><span style="white-space:pre-wrap"></span>MPI_Comm_size(server, &size);</div>
<div><span style="white-space:pre-wrap"></span>printf("At client, server_size=%d @ MPI_COMM_WORLD=%x, Server_World=%x\n",size,MPI_COMM_WORLD,server);</div>
<div><br>
</div>
<div><span style="white-space:pre-wrap"></span>MPI_Comm_disconnect( &server );</div>
<div><span style="white-space:pre-wrap"></span>MPI_Finalize();</div>
<div><span style="white-space:pre-wrap"></span>return 0;</div>
<div>}</div>
</div>
<div><br>
</div>
<div>The run command is as following.</div>
<div>mpiexec -n 1 ./server</div>
<div>mpiexec -n 1 ./client</div>
<div><br>
</div>
<div>BUT, the SIZE is 1, NOT 2.</div>
<div><br>
</div>
<div>My question is as before: How does the size of MPI_COMM_WORLD change to 2 ?</div><div><div class="h5">
<br>
<div></div>
<div></div>
<br>
At 2015-01-23 00:30:43, "Huiwei Lu" <<a href="mailto:huiweilu@mcs.anl.gov" target="_blank">huiweilu@mcs.anl.gov</a>> wrote:<br>
<blockquote style="PADDING-LEFT:1ex;MARGIN:0px 0px 0px 0.8ex;BORDER-LEFT:#ccc 1px solid">
<div dir="ltr">You may take a look at MPI_Comm_accept and MPI_Comm_connect, which will connect a new client process to a server process. See Chap. 10 of MPI 3.0 standard (<a href="http://www.mpi-forum.org/docs/mpi-3.0/mpi30-report.pdf" target="_blank">www.mpi-forum.org/docs/mpi-3.0/mpi30-report.pdf</a>)
for a detail example.
<div class="gmail_extra"><br clear="all">
<div>
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<div dir="ltr">
<div>
<div dir="ltr">
<div>
<div dir="ltr">
<div dir="ltr">--</div>
<div dir="ltr">Huiwei Lu</div>
<div dir="ltr">Postdoc Appointee</div>
<div dir="ltr">Mathematics and Computer Science Division</div>
<div dir="ltr">Argonne National Laboratory</div>
<div dir="ltr"><a href="http://www.mcs.anl.gov/~huiweilu/" target="_blank">http://www.mcs.anl.gov/~huiweilu/</a></div>
</div>
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<br>
<div class="gmail_quote">On Thu, Jan 22, 2015 at 9:41 AM, haozi <span dir="ltr"><<a href="mailto:yidanyiji@163.com" target="_blank">yidanyiji@163.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="line-height:1.7;color:#000000;font-size:14px;font-family:Arial">
<div style="line-height:1.7;color:#000000;font-size:14px;font-family:Arial">
<div>Hi, guys.</div>
<div><br>
</div>
<div>This web page (<a href="http://wiki.mpich.org/mpich/index.php/PMI_v2_Design_Thoughts)" target="_blank">http://wiki.mpich.org/mpich/index.php/PMI_v2_Design_Thoughts)</a> says:</div>
<div> <b> </b><span style="font-family:sans-serif;font-size:12.8000001907349px;line-height:19.2000007629395px"><b>Singleton init.</b> This is the process by which a program that was not started with mpiexec can
<b>become an MPI process </b>and make use of all MPI features, including MPI_Comm_spawn, needs to be designed and documented, with particular attention to the disposition of standard I/O. Not all process managers will want to or even be able to create a new
mpiexec process, so this needs to be negotiated. Similarly, the dispostion of stdio needs to be negotiated between the singleton process and the process manager. To address these issues, a new singleton init protocol has been implemented and tested with the
gforker process manager.</span></div>
<div><br>
</div>
<div>I am very interested in this <font color="#333333" face="arial"><span style="line-height:22px;background-color:rgb(254,254,254)">function</span></font>.</div>
<div>Can this function solve the following question:</div>
<div> At beginning, the MPI job uses the mpiexec commond to start three MPI processes. That is to say, there are three MPI processes in MPI_COMM_WORLD. At some time, the job find itself to need another MPI process to cooperate the three MPI processes.
So the question is: Could PMI help an non-MPI process to become a MPI process of the current MPI_COMM_WORLD? That is to say, Could the non-MPI process use the PMI function to become a member process of the current MPI job which would have FOUR MPI processes
in MPI_COMM_WORLD?</div>
<div><br>
</div>
<div>Is there some method to solve question?</div>
<div>Is anybody have some example?</div>
<div><br>
</div>
<div>Thandks!!!</div>
</div>
</div>
<br>
<br>
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