I've noticed that one *some* z/OS systems that the first call to the resolver by a Unix process takes an extra 1/2 second or more. Does anyone have any clues as to why this would be?
I have a tiny test program that demonstrates. It calls getaddrinfo(127.0.0.1) twice. I've highlighted the lines in the resolver trace output below that wrap the lost time (577 ms). The time is lost regardless of whether I run this without the resolver trace. On another z/OS system, this same section (before res_init Started) takes less than 2 ms. Also, if I run the program multiple times from the same shell with _BPX_SHAREAS=YES, each run demonstrates the problem. So the lost time is per-process and not per-address space. Thanks, Kirk Wolf Dovetailed Technologies http://dovetail.com > make c99 -o getaddrinfo-test getaddrinfo-test.c sh -c "RESOLVER_TRACE=STDOUT time getaddrinfo-test" 2019/01/22 17:11:36.770698 - getaddrinfo-test: count=1 *Resolver Trace Initialization Complete -> 2019/01/22 17:11:36.770841 * res_init Resolver values: Setup file warning messages = No CTRACE TRACERES option = No Global Tcp/Ip Dataset = VENDOR.TCPIP.DATA Default Tcp/Ip Dataset = TCPIP.TCPIP.DATA Local Tcp/Ip Dataset = None Translation Table = TCPIP.STANDARD.TCPXLBIN UserId/JobName = KIRK Caller API = LE C Sockets Caller Mode = EBCDIC System Name = S0W1 (from VMCF) UnresponsiveThreshold = 25 (G) DataSetPrefix = TCPIP (G) HostName = ZOSDTL22 (G) TcpIpJobName = TCPIP (G) DomainOrigin = DOVETAIL.COM (G) NameServer = 8.8.8.8 EDNS0 Support = Unknown 4.4.4.4 EDNS0 Support = Unknown (G) NsPortAddr = 53 (G) ResolverTimeout = 30 (G) ResolveVia = UDP (G) ResolverUdpRetries = 1 (*) Options NDots = 1 (*) SockNoTestStor (*) AlwaysWto = NO (*) MessageCase = MIXED (G) LookUp = DNS (*) Cache (*) NoCacheReorder res_init Succeeded *res_init Started: 2019/01/22 17:11:37.347882* res_init Ended: 2019/01/22 17:11:37.347886 *************************************************************************** GetAddrInfo Started: 2019/01/22 17:11:37.347910 GetAddrinfo Invoked with following inputs: Host Name: 127.0.0.1 Service Name: 22 Hints parameter supplied with settings: ai_family = 0, ai_flags = 0x00000000 ai_protocol = 0, ai_socktype = 1 GetAddrinfo Input Does Not Require Socket GetAddrInfo Formatting Input IP address GetAddrInfo Utilizing Input Port Number GetAddrInfo Built 1 Addrinfos GetAddrInfo Succeeded: IP Address(es) found: IP Address(1) is 127.0.0.1 GetAddrInfo Ended: 2019/01/22 17:11:37.347955 *************************************************************************** 2019/01/22 17:11:37.347973 - getaddrinfo-test: result = 127.0.0.1 2019/01/22 17:11:37.347987 - getaddrinfo-test: count=2 GetAddrInfo Started: 2019/01/22 17:11:37.348108 GetAddrinfo Invoked with following inputs: Host Name: 127.0.0.1 Service Name: 22 Hints parameter supplied with settings: ai_family = 0, ai_flags = 0x00000000 ai_protocol = 0, ai_socktype = 1 GetAddrinfo Input Does Not Require Socket GetAddrInfo Formatting Input IP address GetAddrInfo Utilizing Input Port Number GetAddrInfo Built 1 Addrinfos GetAddrInfo Succeeded: IP Address(es) found: IP Address(1) is 127.0.0.1 GetAddrInfo Ended: 2019/01/22 17:11:37.348127 *************************************************************************** 2019/01/22 17:11:37.348139 - getaddrinfo-test: result = 127.0.0.1 real 0m 0.56s user 0m 0.00s sys 0m 0.00s PS> Here's the Makefile and program if you want to try it on your system # file: Makefile # Note: indented lines must be tab character all: run run: build sh -c "RESOLVER_TRACE=STDOUT time getaddrinfo-test" build: getaddrinfo-test getaddrinfo-test: getaddrinfo-test.c c99 -o getaddrinfo-test getaddrinfo-test.c /* file: getaddrinfo-test.c */ #define _OPEN_SYS_SOCK_IPV6 #define _XOPEN_SOURCE_EXTENDED 1 #include <stdio.h> #include <stddef.h> #include <stdlib.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> #include <netdb.h> #include <sys/types.h> #include <arpa/inet.h> #include <time.h> #undef _ALL_SOURCE #include <sys/time.h> static void usage() { fprintf(stderr, "usage: getaddrinfo-test host port\n"); exit(1); } static char* getTimestamp() { struct timeval curTime; time_t rawtime; struct tm * timeinfo; char buffer [80]; char result [100]; gettimeofday(&curTime, NULL); time(&rawtime); timeinfo = localtime(&rawtime); strftime(buffer, sizeof(buffer), "%Y/%m/%d %H:%M:%S", timeinfo); snprintf(result, sizeof(result), "%s.%6.6u", buffer, curTime.tv_usec); return result; } int main(int ac, char **av) { struct addrinfo hints, *ai, *aitop; struct sockaddr_in *saddr_in; int gaierr; int i; char* addr = "127.0.0.1"; char* port = "22"; switch (ac) { case 3: port = av[2]; case 2: addr = av[1]; case 1: break; default: usage(); } for (i=0; i<2; i++) { printf("%s - getaddrinfo-test: count=%d\n", getTimestamp(), i+1); memset(&hints, 0, sizeof(hints)); hints.ai_family = AF_UNSPEC; hints.ai_socktype = SOCK_STREAM; hints.ai_flags = 0; if ((gaierr = getaddrinfo(addr, port, &hints, &aitop)) != 0) { fprintf(stderr, "%s - getaddrinfo-test: bad addr or host: %s:%s (%s)\n", getTimestamp(), __func__, addr ? addr : "<NULL>", port ? port : "<NULL>", strerror(gaierr)); return 1; } saddr_in = (struct sockaddr_in *)aitop->ai_addr; printf("%s - getaddrinfo-test: result = %s\n", getTimestamp(), inet_ntoa(saddr_in->sin_addr)); } return 0; } ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
