Hi,
I have a client-server socket program. It has been working fine for over a year, but recently it started to show strange behavior.
After the server program runs for a while, it will show in the top command saying it is using lots of CPU, MEM. I assume it means the server code is processing some requests. But I never sent a request from the client side(from a web page). When this happens, I try to send a request to the server, the server won't response. I looked at the output from the server side, it shows the accept was called before, though I didn't send any connect calls from the client. I guess the server stopped at the read().
Parts of the program is:
void CServer_pth::run_pth(Nabor_pth *Nab, Bool_pth *Bl, BnBayes_pth *Bnb, Focus_pth *Foc, Slice_Accpth *Sac) {
int i, nsid;
pNab = Nab;
pBl = Bl;
pBnb = Bnb;
pFoc = Foc;
pSac = Sac;
//create a stream socket
// Sock sp(AF_INET, SOCK_STREAM, 0);
if (!sp.good()) {
cout<<"sp.good() failed\n";
exit(1);
}
//Bind a name to the server socket
if (sp.bind(host, port) < 0) {
cout<<"sp.bind failed\n";
sp.~Sock();
exit(2);
}
for (i=0; i<NUM_THR; i++) {
if (pthread_create(&srvtid[i], &thread_attr, commsrv_pth,tdata[i])) {
perror("pthread_create");
cout<<"srvtid[i], i="<<i<<endl;
cout<<"error in pthread_create, in commsrv_pth\n";
exit(1);
}
}
sem_init(&smp,0, NUM_THR);
for (;
{
sem_wait\(&smp\);
while \(\(nsid = sp.accept\(0, 0\)\) < 0\) \{
cout<<"accept failed\\n";
exit\(1\);
\}
bot = bot%NUM_THR;
i = mat[bot];
cout<<"i in nsid ----> "<<i<<"\\tnsid ---> "<<nsid<<endl;
*tdata [i]= nsid;
bot\+\+;
pthread\_mutex_lock\(&mthread\);
pthread\_cond_signal\(&cond\);
pthread\_mutex_unlock\(&mthread\);
}
}
extern "C" void *commsrv_pth(void *argp) {
cmd_Query cmd;
int i, t_nsid;
while (1) {
pthread\_mutex_lock\(&mthread\);
pthread\_cond_wait\(&cond, &mthread\);
pthread\_mutex_unlock\(&mthread\);
pthread\_mutex_lock\(&mbotp\);
botp = botp%NUM_THR;
i = mat[botp];
t_nsid = *tdata[i];
botp\+\+;
pthread\_mutex_unlock\(&mbotp\);
cout<<"i in nsid ----> "<<i<<"\\tnsid ---> "<<t_nsid<<endl;
cout<<"wait to read MSG from a client socket\n";
// read MSG1 from a client socket
if \(sp.read\(\(char*\)&cmd, sizeof\(cmd_Query\), 0,t_nsid\) < 0\) \{
cout<<"failed in read\\n";
return \(int*\)5;
\}
cout<<"after waiting to read\n";
cmd = \(cmd_Query\)ntohl\(cmd\);
dispatch_pth\(cmd, t_nsid\);
close\(t_nsid\);
pthread\_mutex_lock\(&mtop\);
top = top%NUM_THR;
mat[top] = i;
top\+\+;
pthread\_mutex_unlock\(&mtop\);
sem_post\(&smp\);
}
return NULL;
}
The above is creating 5(NUM_THR) threads first, then wait the call from clients. I also tried another way which is createing one thread at a time when there's a call from the client. But the same strange behaviour happeded.
void CServer_pth::run_pth(Nabor_pth *pNab, Bool_pth *pBl, BnBayes_pth *pBnb, Focus_pth *pFoc, Slice_Accpth *pSac) {
int i, nsid;
//create a stream socket
Sock sp(AF_INET, SOCK_STREAM, 0);
if (!sp.good()) {
cout<<"sp.good() failed\n";
//return 1;
}
//Bind a name to the server socket
if (sp.bind(host, port) < 0) {
cout<<"sp.bind failed\n";
//return 2;
}
for (i=0; i<NUM_THR; i++) {
tdata [i]= new Thrdata_pth(sp, pNab, pBl, pBnb, pFoc, pSac, i); }
sem_init(&smp,0, NUM_THR);
for (; {
while ((nsid = sp.accept(0, 0)) < 0) {
cout<<"accept failed\n";
//return 1;
}
sem_wait\(&smp\);
bot = bot%NUM_THR;
i = mat[bot];
cout<<"i in nsid ----> "<<i<<"\tnsid ---> "<<nsid<<endl;
tdata[i]->set_nsid(nsid);
if (pthread_create(&srvtid[i], &thread_attr, commsrv_pth,tdata[i])) {
perror("pthread_create");
cout<<"srvtid[i], i="<<i<<endl;
cout<<"error in pthread_create, in commsrv_pth\n";
exit(1);
}
bot++;
}
}
extern "C" void *commsrv_pth(void *argp) {
Thrdata_pth data = (Thrdata_pth)argp;
cmd_Query cmd;
cout<<"waiting for reading cmd_Query from a client\n";
// read MSG1 from a client socket
if ((data->t_sp).read((char*)&cmd, sizeof(cmd_Query), 0,data->t_nsid) < 0) {
cout<<"failed in read\n";
return (int*)5;
}
cmd = (cmd_Query)ntohl(cmd);
dispatch_pth(cmd, data);
close(data->t_nsid);
pthread_mutex_lock(&mtop);
top = top%NUM_THR;
mat[top] = data->iz;
top++;
pthread_mutex_unlock(&mtop);
sem_post(&smp);
return NULL;
}
Any advice? Thanks very much for help!!!