int wait_for_signal(MPI_Comm comm, int signal_num) {
int new_failures, ret;
MPI_Status status;
while(cur_epoch < signal_num) {
/*
* MPI_Probe is a blocking call that will unblock when it encounters an
* error on the indicated peer. By passing MPI_ANY_SOURCE, it will cause
* MPI_Probe to unblock on the first un-recognized failed process.
*
* The error handler will be called before MPI_Probe returns.
*
* In this example, MPI_Probe will only return when there is an error
* since we do not send messages in this example. But we check the
* return code anyway, just for good form.
*/
ret = MPI_Probe(MPI_ANY_SOURCE, TAG_FT_DETECT, comm, &status);
if( MPI_SUCCESS != ret ) {
printf("%2d of %2d) MPI_Probe() Error: Some rank failed (error = %3d)\n",
mpi_mcw_rank, mpi_mcw_size,
status.MPI_ERROR);
/* Recognize the failure and move on */
OMPI_Comm_failure_ack(comm);
}
sleep(1);
}
return 0;
}
int numProcsFails(MPI_Comm mcw){
int rank, ret, numFailures = 0, flag;
MPI_Group fGroup;
MPI_Errhandler newEh;
MPI_Comm dupComm;
// Error handler
MPI_Comm_create_errhandler(mpiErrorHandler, &newEh);
MPI_Comm_rank(mcw, &rank);
// Set error handler for communicator
MPI_Comm_set_errhandler(mcw, newEh);
// Target function
if(MPI_SUCCESS != (ret = MPI_Comm_dup(mcw, &dupComm))) {
//if(MPI_SUCCESS != (ret = MPI_Barrier(mcw))) { // MPI_Comm_dup or MPI_Barrier
OMPI_Comm_failure_ack(mcw);
OMPI_Comm_failure_get_acked(mcw, &fGroup);
// Get the number of failures
MPI_Group_size(fGroup, &numFailures);
}// end of "MPI_Comm_dup failure"
OMPI_Comm_agree(mcw, &flag);
// Memory release
if(numFailures > 0)
MPI_Group_free(&fGroup);
MPI_Errhandler_free(&newEh);
return numFailures;
}//numProcsFails()
void mpiErrorHandler(MPI_Comm * comm, int *errorCode, ...){
MPI_Group failedGroup;
OMPI_Comm_failure_ack(*comm);
OMPI_Comm_failure_get_acked(*comm, &failedGroup);
// *errorCode == MPI_ERR_PROC_FAILED classify failure type as "process" failure
// Failed processes will NOT be synchronized Without delay
// This delay MUST be through error handler (otherwise, problematic)
usleep(10000); // 10 milliseconds delay (MPI_Comm_revoke is failed without
// this for a large number of processes)
MPI_Group_free(&failedGroup);
return;
}//mpiErrorHandler()
void mpi_error_handler(MPI_Comm *comm, int *error_code, ...)
{
MPI_Group f_group;
int num_failures;
int loc_size;
char * ranks_failed = NULL;
MPI_Comm_size(*comm, &loc_size);
/*
* Will cause normal termination by unblocking the wait_for_signal() function
* when all process failures have been reported.
*/
cur_epoch++;
printf("Handler !!\n");
fflush(NULL);
if(*error_code == MPI_ERR_PROC_FAILED ) {
/* Access the local list of failures */
OMPI_Comm_failure_ack(*comm);
OMPI_Comm_failure_get_acked(*comm, &f_group);
/* Get the number of failures */
MPI_Group_size(f_group, &num_failures);
cur_epoch = num_failures;
ranks_failed = get_str_failed_procs(*comm, f_group);
printf("%2d of %2d) Error Handler: (Comm = %s) %3d Failed Ranks: %s\n",
mpi_mcw_rank, mpi_mcw_size,
(mpi_mcw_size == loc_size ? "MCW" : "Subcomm"),
num_failures, ranks_failed);
free(ranks_failed);
} else {
printf("%2d of %2d) Error Handler: Some Other error has occurred. (Comm = %s) [Count = %2d / %2d]\n",
mpi_mcw_rank, mpi_mcw_size,
(mpi_mcw_size == loc_size ? "MCW" : "Subcomm"), cur_epoch, max_signals );
}
/* Introduce a small delay to aid debugging */
fflush(NULL);
sleep(1);
return;
}
void mpiErrorHandler(MPI_Comm * comm, int *errorCode, ...) {
MPI_Group failedGroup;
OMPI_Comm_failure_ack(*comm);
OMPI_Comm_failure_get_acked(*comm, &failedGroup);
/*
int rank, nprocs;
MPI_Comm_rank(*comm, &rank);
MPI_Comm_size(*comm, &nprocs);
if(*errorCode == MPI_ERR_PROC_FAILED ) {
printf("(Process %d of %d) C Error Handler: MPI_ERROR_PROC_FAILED Detected.\n",
rank, nprocs);
}
else {
printf("(Process %d of %d) C Error Handler: Other Failure Detected.\n",
rank, nprocs);
}
*/
// Introduce a small delay to aid debugging
fflush(NULL);
// 1. Without delay, failed processes will NOT be synchronized.
// 2. This delay MUST be through error handler. Otherwise, NOT work.
// 3. 10 milliseconds is the minimum delay I have tested on a dual-core machine
// for 200 processes. Not working if smaller time is given.
//sleep(1); // 1 second
usleep(10000); // # 10 milliseconds
// # MPI_Comm_revoke is failed without this for a large number of
// processes, but works for 1 process failure.
// # most of the time hangs on for more than 1 process failure without this.
// # necessary to enable this for a small number of processes to test.
MPI_Group_free(&failedGroup);
return;
}//mpiErrorHandler()
void repairComm(MPI_Comm * broken, MPI_Comm * repaired, int iteration, int * listFails, int * numFails,
int * numNodeFails, int sumPrevNumNodeFails, int argc, char ** argv, int verbosity) {
MPI_Comm tempShrink, unorderIntracomm, tempIntercomm;
int i, ret, result, procsNeeded = 0, oldRank, newRank, oldGroupSize, rankKey = 0, flag;
int * tempRanks, * failedRanks, * errCodes, rank, hostfileLineIndex;
MPI_Group oldGroup, failedGroup, shrinkGroup;
int hostfileLastLineIndex, tempLineIndex, * failedNodeList = NULL, * nodeList = NULL, totNodeFailed = 0;
double startTime = 0.0, endTime;
int nprocs, j, * shrinkMergeList;
char hostName[128];
gethostname(hostName, sizeof(hostName));
char ** appToLaunch;
char *** argvToLaunch;
int * procsNeededToLaunch;
MPI_Info * hostInfoToLaunch;
char ** hostNameToLaunch;
MPI_Comm_rank(*broken, &rank);
if(rank == 0)
startTime = MPI_Wtime();
#ifndef GLOBAL_DETECTION
MPI_Comm_size(*broken, &oldGroupSize);
MPI_Comm_group(*broken, &oldGroup);
MPI_Comm_rank(*broken, &oldRank);
OMPI_Comm_failure_ack(*broken);
OMPI_Comm_failure_get_acked(*broken, &failedGroup);
MPI_Group_size(failedGroup, &procsNeeded);
errCodes = (int *) malloc(sizeof(int) * procsNeeded);
// Figure out ranks of the processes which had failed
tempRanks = (int *) malloc(sizeof(int) * oldGroupSize);
failedRanks = (int *) malloc(sizeof(int) * oldGroupSize);
#pragma omp parallel for default(shared)
for(i = 0; i < oldGroupSize; i++)
tempRanks[i] = i;
MPI_Group_translate_ranks(failedGroup, procsNeeded, tempRanks, oldGroup, failedRanks);
#endif
double shrinkTime = MPI_Wtime();
// Shrink the broken communicator to remove failed procs
if(MPI_SUCCESS != (ret = OMPI_Comm_shrink(*broken, &tempShrink)))
printf("Iteration %d: OMPI_Comm_shrink (parent): ERROR!\n", iteration);
else {
if(verbosity > 1 )
printf("Iteration %d: OMPI_Comm_shrink (parent): SUCCESS\n", iteration);
}
if (verbosity > 0 && rank == 0)
printf("OMPI_Comm_shrink takes %0.6f Sec\n", MPI_Wtime() - shrinkTime);
#ifdef GLOBAL_DETECTION
MPI_Comm_group(*broken, &oldGroup);
MPI_Comm_group(tempShrink, &shrinkGroup);
MPI_Comm_size(*broken, &oldGroupSize);
MPI_Group_compare(oldGroup, shrinkGroup, &result);
if(result != MPI_IDENT)
MPI_Group_difference(oldGroup, shrinkGroup, &failedGroup);
MPI_Comm_rank(*broken, &oldRank);
MPI_Group_size(failedGroup, &procsNeeded);
errCodes = (int *) malloc(sizeof(int)*procsNeeded);
// Figure out ranks of the processes which had failed
tempRanks = (int*)malloc(sizeof(int)*oldGroupSize);
failedRanks = (int*)malloc(sizeof(int)*oldGroupSize);
#pragma omp parallel for default(shared)
for(i = 0; i < oldGroupSize; i++)
tempRanks[i] = i;
MPI_Group_translate_ranks(failedGroup, procsNeeded, tempRanks, oldGroup, failedRanks);
MPI_Group_free(&shrinkGroup);
#endif
// Assign number of failed processes
*numFails = procsNeeded;
hostNameToLaunch = (char **) malloc(procsNeeded * sizeof(char *));
if(verbosity > 0 && rank == 0)
printf("*** Iteration %d: Application: Number of process(es) failed in the corresponding "
"communicator is %d ***\n", iteration, procsNeeded);
if(rank == 0) {
endTime = MPI_Wtime();
printf("[%d]----- Creating failed process list takes %0.6f Sec (MPI_Wtime) -----\n", rank, endTime - startTime);
}
#ifdef RECOV_ON_SPARE_NODES
// Determining total number of node failed, and a list of them
hostfileLastLineIndex = getHostfileLastLineIndex(); //started from 0
nodeList = (int *) malloc((hostfileLastLineIndex+1) * sizeof(int));
memset(nodeList, 0, (hostfileLastLineIndex+1)*sizeof(int)); // initialize nodeList with 0's
for(int i = 0; i < procsNeeded; ++i) {
tempLineIndex = failedRanks[i]/SLOTS; //started from 0
nodeList[tempLineIndex] = 1;
}
for(int nodeCounter = 0; nodeCounter < (hostfileLastLineIndex+1); ++nodeCounter)
totNodeFailed += nodeList[nodeCounter];
*numNodeFails = totNodeFailed;
// Check if there is sufficient spare node available for recovery
if((hostfileLastLineIndex - totNodeFailed -sumPrevNumNodeFails) < (oldGroupSize-1)/SLOTS) {
if(rank == 0)
printf("[%d] There is no sufficient spare node available for recovery.\n", rank);
exit(0);
}
failedNodeList = (int *) malloc(totNodeFailed * sizeof(int));
memset(failedNodeList, 0, totNodeFailed * sizeof(int)); // initialize failedNodeList with 0's
int failedNodeCounter = 0;
for(int nodeCounter = 0; nodeCounter < (hostfileLastLineIndex+1); ++nodeCounter) {
if(nodeList[nodeCounter] == 1)
failedNodeList[failedNodeCounter++] = nodeCounter;
}
#endif
char * hostNameFailed = NULL;
#pragma omp parallel for default(shared)
for(i = 0; i < procsNeeded; ++i) {
// Assign list of processes failed
listFails[i] = failedRanks[i];
#ifdef RUN_ON_COMPUTE_NODES
tempLineIndex = failedRanks[i]/SLOTS; //started from 0
#ifdef RECOV_ON_SPARE_NODES
for(int j = 0; j < totNodeFailed; ++j) {
if(failedNodeList[j] == tempLineIndex)
hostfileLineIndex = hostfileLastLineIndex - j - sumPrevNumNodeFails;
}
#else // Recovery on the same node (no node failure, only process failure)
hostfileLineIndex = tempLineIndex;
#endif
hostNameToLaunch[i] = getHostToLaunch(hostfileLineIndex);
hostNameFailed = getHostToLaunch(tempLineIndex);
#else // Run on head node or personal machine
hostNameToLaunch[i] = (char *)hostName;
hostNameFailed = (char *)hostName;
#endif
if(verbosity > 0 && rank == 0)
printf("--- Iteration %d: Application: Process %d on node %s is failed! ---\n", iteration, failedRanks[i], hostNameFailed);
}
// Release memory of hostNameFailed
free(hostNameFailed);
appToLaunch = (char **) malloc(procsNeeded * sizeof(char *));
argvToLaunch = (char ***) malloc(procsNeeded * sizeof(char **));
procsNeededToLaunch = (int *) malloc(procsNeeded * sizeof(int));
hostInfoToLaunch = (MPI_Info *) malloc(procsNeeded * sizeof(MPI_Info));
argv[argc] = NULL;
#pragma omp parallel for default(shared)
for(i = 0; i < procsNeeded; i++) {
appToLaunch[i] = (char *)argv[0];
argvToLaunch[i] = (char **)argv;
procsNeededToLaunch[i] = 1;
// Host information where to spawn the processes
MPI_Info_create(&hostInfoToLaunch[i]);
MPI_Info_set(hostInfoToLaunch[i], (char *)"host", hostNameToLaunch[i]);
//MPI_Info_set(hostInfoToLaunch[i], "hostfile", "hostfile");
}
double spawnTime = MPI_Wtime();
#ifdef HANG_ON_REMOVE
OMPI_Comm_agree(tempShrink, &flag);
#endif
// Spawn the new process(es)
if(MPI_SUCCESS != (ret = MPI_Comm_spawn_multiple(procsNeeded, appToLaunch, argvToLaunch, procsNeededToLaunch,
hostInfoToLaunch, 0, tempShrink, &tempIntercomm, MPI_ERRCODES_IGNORE))) {
free(tempRanks);
free(failedRanks);
free(errCodes);
if(MPI_ERR_COMM == ret)
printf("Iteration %d: MPI_Comm_spawn_multiple: Invalid communicator (parent)\n", iteration);
if(MPI_ERR_ARG == ret)
printf("Iteration %d: MPI_Comm_spawn_multiple: Invalid argument (parent)\n", iteration);
if(MPI_ERR_INFO == ret)
printf("Iteration %d: MPI_Comm_spawn_multiple: Invalid info (parent)\n", iteration);
if((MPI_ERR_PROC_FAILED == ret) || (MPI_ERR_REVOKED == ret)) {
OMPI_Comm_revoke(tempShrink);
return repairComm(broken, repaired, iteration, listFails, numFails, numNodeFails,
sumPrevNumNodeFails, argc, argv, verbosity);
}
else {
fprintf(stderr, "Iteration %d: Unknown error with MPI_Comm_spawn_multiple (parent): %d\n", iteration, ret);
exit(1);
}
}
else {
if(verbosity > 0 && rank == 0) {
for(i = 0; i < procsNeeded; i++)
printf("Iteration %d: MPI_Comm_spawn_multiple (parent) [spawning failed process %d on "
"node %s]: SUCCESS\n", iteration, failedRanks[i], hostNameToLaunch[i]);
}
// Memory release. Moving the last two to the end of the function causes segmentation faults for 4 processes failure
}
if (verbosity > 0 && rank == 0)
printf("MPI_Comm_spawn_multiple takes %0.6f Sec\n", MPI_Wtime() - spawnTime);
double mergeTime = MPI_Wtime();
// Merge the new processes into a new communicator
if(MPI_SUCCESS != (ret = MPI_Intercomm_merge(tempIntercomm, false, &unorderIntracomm))) {
free(tempRanks);
free(failedRanks);
if((MPI_ERR_PROC_FAILED == ret) || (MPI_ERR_REVOKED == ret)) {
// Start the recovery over again if there is a failure
OMPI_Comm_revoke(tempIntercomm);
return repairComm(broken, repaired, iteration, listFails, numFails,
numNodeFails, sumPrevNumNodeFails, argc, argv, verbosity);
}
else if(MPI_ERR_COMM == ret) {
fprintf(stderr, "Iteration %d: Invalid communicator in MPI_Intercomm_merge (parent) %d\n", iteration, ret);
exit(1);
}
else if(MPI_ERR_INTERN == ret) {
fprintf(stderr, "Iteration %d: Acquaring memory error in MPI_Intercomm_merge ()%d\n", iteration, ret);
exit(1);
}
else {
fprintf(stderr, "Iteration %d: Unknown error with MPI_Intercomm_merge: %d\n", iteration, ret);
exit(1);
}
}
else {
if(verbosity > 1 )
printf("Iteration %d: MPI_Intercomm_merge (parent): SUCCESS\n", iteration);
}
if (verbosity > 0 && rank == 0)
printf("MPI_Intercomm_merge takes %0.6f Sec\n", MPI_Wtime() - mergeTime);
double agreeTime = MPI_Wtime();
// Synchronize. sometimes hangs in without this
// position of code and intercommunicator (not intra) is important
#ifdef HANG_ON_REMOVE
//MPI_Barrier(tempIntercomm);
OMPI_Comm_agree(tempIntercomm, &flag);// since some of the times MPI_Barrier hangs
#endif
if (verbosity > 0 && rank == 0)
printf("OMPI_Comm_agree takes %0.6f Sec\n", MPI_Wtime() - agreeTime);
// Sending failed ranks and number of processes failed to the the newly created ranks.
// oldGroupSize is the size of communicator before failure.
// procsNeeded is the number of processes that are failed
int * child = (int *) malloc(procsNeeded*sizeof(int));
#pragma omp parallel for default(shared)
for(i = 0; i < procsNeeded; i++)
child[i] = oldGroupSize - procsNeeded + i;
MPI_Comm_rank(unorderIntracomm, &newRank);
if(newRank == 0) {
int send_val[2];
for(i = 0; i < procsNeeded; i++) {
send_val[0] = failedRanks[i];
send_val[1] = procsNeeded;
if(MPI_SUCCESS != (ret = MPI_Send(&send_val, 2, MPI_INT, child[i], MERGE_TAG, unorderIntracomm))) {
free(tempRanks);
free(failedRanks);
if((MPI_ERR_PROC_FAILED == ret) || (MPI_ERR_REVOKED == ret)) {
// Start the recovery over again if there is a failure
OMPI_Comm_revoke(unorderIntracomm);
return repairComm(broken, repaired, iteration, listFails, numFails,
numNodeFails, sumPrevNumNodeFails, argc, argv, verbosity);
}
else {
fprintf(stderr, "Iteration %d: Unknown error with MPI_Send1 (parent): %d\n", iteration, ret);
exit(1);
}
}
else {
if(verbosity > 1 )
printf("Iteration %d: MPI_Send1 (parent): SUCCESS\n", iteration);
}
}
}
// Split the current world (splitted from original) to order the ranks.
MPI_Comm_rank(unorderIntracomm, &newRank);
MPI_Comm_size(unorderIntracomm, &nprocs);
// For one or more process failure (ordering)
shrinkMergeList = (int *) malloc(nprocs*sizeof(int));
j = 0;
for(i = 0; i < nprocs; i++) {
if(rankIsNotOnFailedList(i, failedRanks, procsNeeded))
shrinkMergeList[j++] = i;
}
for(i = j; i < nprocs; i++)
shrinkMergeList[i] = failedRanks[i-j];
for(i = 0; i < (nprocs - procsNeeded); i++) {
if(newRank == i)
rankKey = shrinkMergeList[i];
}
if(MPI_SUCCESS != (MPI_Comm_split(unorderIntracomm, 0, rankKey, repaired))) {
if((MPI_ERR_PROC_FAILED == ret) || (MPI_ERR_REVOKED == ret)) {
// Start the recovery over again if there is a failure
OMPI_Comm_revoke(unorderIntracomm);
return repairComm(broken, repaired, iteration, listFails, numFails,
numNodeFails, sumPrevNumNodeFails, argc, argv, verbosity);
}
else {
fprintf(stderr, "Iteration %d: Unknown error with MPI_Comm_split (parent): %d\n", iteration, ret);
exit(1);
}
}
else {
if(verbosity > 1 )
printf("Iteration %d: MPI_Comm_split (parent): SUCCESS\n", iteration);
}
// Release memory
free(appToLaunch);
free(argvToLaunch);
free(procsNeededToLaunch);
free(hostInfoToLaunch);
free(hostNameToLaunch);
free(shrinkMergeList);
free(errCodes);
MPI_Comm_free(&tempShrink);
free(tempRanks);
free(failedRanks);
free(child);
MPI_Group_free(&failedGroup);
MPI_Group_free(&oldGroup);
MPI_Comm_free(&tempIntercomm);
MPI_Comm_free(&unorderIntracomm);
#ifdef RECOV_ON_SPARE_NODES
if(failedNodeList != NULL)
free(failedNodeList);
if(nodeList != NULL)
free(nodeList);
#endif
}//repairComm()
