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• Apache will not stop/start gracefully

  - by ddjammin

  CentOs 6 64bit running apache 2.2.15-29.el6.centos. When I try to stop/start or restart httpd I get an error that says it has failed. A tail of the error log is below. I also noticed that a httpd.pid file is not created even though it is configured in the main conf file. If I set selinux to permissive, it works just fine. I do not want to run it with selinux disabled. If I delete the SSL_Mutex file it will start. HTTPD was running fine until I tried to add the ssl configuration. I copied over the ssl.conf file from a working server into the conf.d folder. I also copied a sslcert folder into the conf folder. It contains the certs, key, csr and password file. I think the problem has to do with the selinux context for the sslcert folder that was copied but I am not certain and not sure how to fix it. Below is the security context for the sslcert folder after executing restorecon -R sslcert ls -Z -rw-r--r--. root root system_u:object_r:httpd_config_t:s0 httpd.conf -rw-r--r--. root root system_u:object_r:httpd_config_t:s0 magic **drwxr-xr-x. root root system_u:object_r:httpd_config_t:s0 sslcert** tail -f /var/log/httpd/error_log [Thu Oct 17 13:33:19 2013] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec) [Thu Oct 17 13:33:20 2013] [notice] Digest: generating secret for digest authentication ... [Thu Oct 17 13:33:20 2013] [notice] Digest: done [Thu Oct 17 13:33:20 2013] [warn] pid file /etc/httpd/logs/ssl.pid overwritten -- Unclean shutdown of previous Apache run? [Thu Oct 17 13:33:20 2013] [notice] Apache/2.2.15 (Unix) DAV/2 mod_ssl/2.2.15 OpenSSL/1.0.0-fips configured -- resuming normal operations [Thu Oct 17 21:04:48 2013] [notice] caught SIGTERM, shutting down [Thu Oct 17 21:06:42 2013] [notice] **SELinux policy enabled; httpd running as context system_u:system_r:httpd_t:s0** [Thu Oct 17 21:06:42 2013] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec) [Thu Oct 17 21:06:42 2013] [error] (17)File exists: Cannot create SSLMutex with file `/etc/httpd/logs/ssl_mutex' I also saw mention of possible issues with semaphores. Below is the output of the current semaphores and apache is currently not running. ipcs -s ------ Semaphore Arrays -------- key semid owner perms nsems 0x00000000 0 root 600 1 0x00000000 65537 root 600 1 Finally selinux reports the following error. `sealert -a /var/log/audit/audit.log` 0% donetype=AVC msg=audit(1382034755.118:420400): avc: denied { write } for pid=3393 comm="httpd" name="ssl_mutex" dev=dm-0 ino=9513484 scontext=unconfined_u:system_r:httpd_t:s0 tcontext=unconfined_u:object_r:httpd_log_t:s0 tclass=file **** Invalid AVC allowed in current policy *** 100% doneERROR: failed to read complete file, 1044649 bytes read out of total 1043317 bytes (/var/log/audit/audit.log) found 1 alerts in /var/log/audit/audit.log -------------------------------------------------------------------------------- SELinux is preventing /usr/sbin/httpd from remove_name access on the directory ssl_mutex.

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• Threading across multiple files

  - by Zach M.

  My program is reading in files and using thread to compute the highest prime number, when I put a print statement into the getNum() function my numbers are printing out. However, it seems to just lag no matter how many threads I input. Each file has 1 million integers in it. Does anyone see something apparently wrong with my code? Basically the code is giving each thread 1000 integers to check before assigning a new thread. I am still a C noobie and am just learning the ropes of threading. My code is a mess right now because I have been switching things around constantly. #include <stdio.h> #include <stdlib.h> #include <time.h> #include <string.h> #include <pthread.h> #include <math.h> #include <semaphore.h> //Global variable declaration char *file1 = "primes1.txt"; char *file2 = "primes2.txt"; char *file3 = "primes3.txt"; char *file4 = "primes4.txt"; char *file5 = "primes5.txt"; char *file6 = "primes6.txt"; char *file7 = "primes7.txt"; char *file8 = "primes8.txt"; char *file9 = "primes9.txt"; char *file10 = "primes10.txt"; char **fn; //file name variable int numberOfThreads; int *highestPrime = NULL; int fileArrayNum = 0; int loop = 0; int currentFile = 0; sem_t semAccess; sem_t semAssign; int prime(int n)//check for prime number, return 1 for prime 0 for nonprime { int i; for(i = 2; i <= sqrt(n); i++) if(n % i == 0) return(0); return(1); } int getNum(FILE* file) { int number; char* tempS = malloc(20 *sizeof(char)); fgets(tempS, 20, file); tempS[strlen(tempS)-1] = '\0'; number = atoi(tempS); free(tempS);//free memory for later call return(number); } void* findPrimality(void *threadnum) //main thread function to find primes { int tNum = (int)threadnum; int checkNum; char *inUseFile = NULL; int x=1; FILE* file; while(currentFile < 10){ if(inUseFile == NULL){//inUseFIle being used to check if a file is still being read sem_wait(&semAccess);//critical section inUseFile = fn[currentFile]; sem_post(&semAssign); file = fopen(inUseFile, "r"); while(!feof(file)){ if(x % 1000 == 0 && tNum !=1){ //go for 1000 integers and then wait sem_wait(&semAssign); } checkNum = getNum(file); /* * * * * I think the issue is here * * * */ if(checkNum > highestPrime[tNum]){ if(prime(checkNum)){ highestPrime[tNum] = checkNum; } } x++; } fclose(file); inUseFile = NULL; } currentFile++; } } int main(int argc, char* argv[]) { if(argc != 2){ //checks for number of arguements being passed printf("To many ARGS\n"); return(-1); } else{//Sets thread cound to user input checking for correct number of threads numberOfThreads = atoi(argv[1]); if(numberOfThreads < 1 || numberOfThreads > 10){ printf("To many threads entered\n"); return(-1); } time_t preTime, postTime; //creating time variables int i; fn = malloc(10 * sizeof(char*)); //create file array and initialize fn[0] = file1; fn[1] = file2; fn[2] = file3; fn[3] = file4; fn[4] = file5; fn[5] = file6; fn[6] = file7; fn[7] = file8; fn[8] = file9; fn[9] = file10; sem_init(&semAccess, 0, 1); //initialize semaphores sem_init(&semAssign, 0, numberOfThreads); highestPrime = malloc(numberOfThreads * sizeof(int)); //create an array to store each threads highest number for(loop = 0; loop < numberOfThreads; loop++){//set initial values to 0 highestPrime[loop] = 0; } pthread_t calculationThread[numberOfThreads]; //thread to do the work preTime = time(NULL); //start the clock for(i = 0; i < numberOfThreads; i++){ pthread_create(&calculationThread[i], NULL, findPrimality, (void *)i); } for(i = 0; i < numberOfThreads; i++){ pthread_join(calculationThread[i], NULL); } for(i = 0; i < numberOfThreads; i++){ printf("this is a prime number: %d \n", highestPrime[i]); } postTime= time(NULL); printf("Wall time: %ld seconds\n", (long)(postTime - preTime)); } } Yes I am trying to find the highest number over all. So I have made some head way the last few hours, rescucturing the program as spudd said, currently I am getting a segmentation fault due to my use of structures, I am trying to save the largest individual primes in the struct while giving them the right indices. This is the revised code. So in short what the first thread is doing is creating all the threads and giving them access points to a very large integer array which they will go through and find prime numbers, I want to implement semaphores around the while loop so that while they are executing every 2000 lines or the end they update a global prime number. #include <stdio.h> #include <stdlib.h> #include <time.h> #include <string.h> #include <pthread.h> #include <math.h> #include <semaphore.h> //Global variable declaration char *file1 = "primes1.txt"; char *file2 = "primes2.txt"; char *file3 = "primes3.txt"; char *file4 = "primes4.txt"; char *file5 = "primes5.txt"; char *file6 = "primes6.txt"; char *file7 = "primes7.txt"; char *file8 = "primes8.txt"; char *file9 = "primes9.txt"; char *file10 = "primes10.txt"; int numberOfThreads; int entries[10000000]; int entryIndex = 0; int fileCount = 0; char** fileName; int largestPrimeNumber = 0; //Register functions int prime(int n); int getNum(FILE* file); void* findPrimality(void *threadNum); void* assign(void *num); typedef struct package{ int largestPrime; int startingIndex; int numberCount; }pack; //Beging main code block int main(int argc, char* argv[]) { if(argc != 2){ //checks for number of arguements being passed printf("To many threads!!\n"); return(-1); } else{ //Sets thread cound to user input checking for correct number of threads numberOfThreads = atoi(argv[1]); if(numberOfThreads < 1 || numberOfThreads > 10){ printf("To many threads entered\n"); return(-1); } int threadPointer[numberOfThreads]; //Pointer array to point to entries time_t preTime, postTime; //creating time variables int i; fileName = malloc(10 * sizeof(char*)); //create file array and initialize fileName[0] = file1; fileName[1] = file2; fileName[2] = file3; fileName[3] = file4; fileName[4] = file5; fileName[5] = file6; fileName[6] = file7; fileName[7] = file8; fileName[8] = file9; fileName[9] = file10; FILE* filereader; int currentNum; for(i = 0; i < 10; i++){ filereader = fopen(fileName[i], "r"); while(!feof(filereader)){ char* tempString = malloc(20 *sizeof(char)); fgets(tempString, 20, filereader); tempString[strlen(tempString)-1] = '\0'; entries[entryIndex] = atoi(tempString); entryIndex++; free(tempString); } } //sem_init(&semAccess, 0, 1); //initialize semaphores //sem_init(&semAssign, 0, numberOfThreads); time_t tPre, tPost; pthread_t coordinate; tPre = time(NULL); pthread_create(&coordinate, NULL, assign, (void**)numberOfThreads); pthread_join(coordinate, NULL); tPost = time(NULL); } } void* findPrime(void* pack_array) { pack* currentPack= pack_array; int lp = currentPack->largestPrime; int si = currentPack->startingIndex; int nc = currentPack->numberCount; int i; int j = 0; for(i = si; i < nc; i++){ while(j < 2000 || i == (nc-1)){ if(prime(entries[i])){ if(entries[i] > lp) lp = entries[i]; } j++; } } return (void*)currentPack; } void* assign(void* num) { int y = (int)num; int i; int count = 10000000/y; int finalCount = count + (10000000%y); int sIndex = 0; pack pack_array[(int)num]; pthread_t workers[numberOfThreads]; //thread to do the workers for(i = 0; i < y; i++){ if(i == (y-1)){ pack_array[i].largestPrime = 0; pack_array[i].startingIndex = sIndex; pack_array[i].numberCount = finalCount; } pack_array[i].largestPrime = 0; pack_array[i].startingIndex = sIndex; pack_array[i].numberCount = count; pthread_create(&workers[i], NULL, findPrime, (void *)&pack_array[i]); sIndex += count; } for(i = 0; i< y; i++) pthread_join(workers[i], NULL); } //Functions int prime(int n)//check for prime number, return 1 for prime 0 for nonprime { int i; for(i = 2; i <= sqrt(n); i++) if(n % i == 0) return(0); return(1); }

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• quartz: preventing concurrent instances of a job in jobs.xml

  - by Jason S

  This should be really easy. I'm using Quartz running under Apache Tomcat 6.0.18, and I have a jobs.xml file which sets up my scheduled job that runs every minute. What I would like to do, is if the job is still running when the next trigger time rolls around, I don't want to start a new job, so I can let the old instance complete. Is there a way to specify this in jobs.xml (prevent concurrent instances)? If not, is there a way I can share access to an in-memory singleton within my application's Job implementation (is this through the JobExecutionContext?) so I can handle the concurrency myself? (and detect if a previous instance is running) update: After floundering around in the docs, here's a couple of approaches I am considering, but either don't know how to get them to work, or there are problems. Use StatefulJob. This prevents concurrent access... but I'm not sure what other side-effects would occur if I use it, also I want to avoid the following situation: Suppose trigger times would be every minute, i.e. trigger#0 = at time 0, trigger #1 = 60000msec, #2 = 120000, #3 = 180000, etc. and the trigger#0 at time 0 fires my job which takes 130000msec. With a plain Job, this would execute triggers #1 and #2 while job trigger #0 is still running. With a StatefulJob, this would execute triggers #1 and #2 in order, immediately after #0 finishes at 130000. I don't want that, I want #1 and #2 not to run and the next trigger that runs a job should take place at #3 (180000msec). So I still have to do something else with StatefulJob to get it to work the way I want, so I don't see much of an advantage to using it. Use a TriggerListener to return true from vetoJobExecution(). Although implementing the interface seems straightforward, I have to figure out how to setup one instance of a TriggerListener declaratively. Can't find the docs for the xml file. Use a static shared thread-safe object (e.g. a semaphore or whatever) owned by my class that implements Job. I don't like the idea of using singletons via the static keyword under Tomcat/Quartz, not sure if there are side effects. Also I really don't want them to be true singletons, just something that is associated with a particular job definition. Implement my own Trigger which extends SimpleTrigger and contains shared state that could run its own TriggerListener. Again, I don't know how to setup the XML file to use this trigger rather than the standard <trigger><simple>...</simple></trigger>.

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• how to deal with the position in a c# stream

  - by CapsicumDreams

  The (entire) documentation for the position property on a stream says: When overridden in a derived class, gets or sets the position within the current stream. The Position property does not keep track of the number of bytes from the stream that have been consumed, skipped, or both. That's it. OK, so we're fairly clear on what it doesn't tell us, but I'd really like to know what it in fact does stand for. What is 'the position' for? Why would we want to alter or read it? If we change it - what happens? In a pratical example, I have a a stream that periodically gets written to, and I have a thread that attempts to read from it (ideally ASAP). From reading many SO issues, I reset the position field to zero to start my reading. Once this is done: Does this affect where the writer to this stream is going to attempt to put the data? Do I need to keep track of the last write position myself? (ie if I set the position to zero to read, does the writer begin to overwrite everything from the first byte?) If so, do I need a semaphore/lock around this 'position' field (subclassing, perhaps?) due to my two threads accessing it? If I don't handle this property, does the writer just overflow the buffer? Perhaps I don't understand the Stream itself - I'm regarding it as a FIFO pipe: shove data in at one end, and suck it out at the other. If it's not like this, then do I have to keep copying the data past my last read (ie from position 0x84 on) back to the start of my buffer? I've seriously tried to research all of this for quite some time - but I'm new to .NET. Perhaps the Streams have a long, proud (undocumented) history that everyone else implicitly understands. But for a newcomer, it's like reading the manual to your car, and finding out: The accelerator pedal affects the volume of fuel and air sent to the fuel injectors. It does not affect the volume of the entertainment system, or the air pressure in any of the tires, if fitted. Technically true, but seriously, what we want to know is that if we mash it to the floor you go faster..

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• OSError : [Errno 38] Function not implemented - Django Celery implementation

  - by Jordan Messina

  I installed django-celery and I tried to start up the worker server but I get an OSError that a function isn't implemented. I'm running CentOS release 5.4 (Final) on a VPS: . broker -> amqp://guest@localhost:5672/ . queues -> . celery -> exchange:celery (direct) binding:celery . concurrency -> 4 . loader -> djcelery.loaders.DjangoLoader . logfile -> [stderr]@WARNING . events -> OFF . beat -> OFF [2010-07-22 17:10:01,364: WARNING/MainProcess] Traceback (most recent call last): [2010-07-22 17:10:01,364: WARNING/MainProcess] File "manage.py", line 11, in <module> [2010-07-22 17:10:01,364: WARNING/MainProcess] execute_manager(settings) [2010-07-22 17:10:01,364: WARNING/MainProcess] File "/usr/local/lib/python2.6/site-packages/django/core/management/__init__.py", line 438, in execute_manager [2010-07-22 17:10:01,364: WARNING/MainProcess] utility.execute() [2010-07-22 17:10:01,364: WARNING/MainProcess] File "/usr/local/lib/python2.6/site-packages/django/core/management/__init__.py", line 379, in execute [2010-07-22 17:10:01,365: WARNING/MainProcess] self.fetch_command(subcommand).run_from_argv(self.argv) [2010-07-22 17:10:01,365: WARNING/MainProcess] File "/usr/local/lib/python2.6/site-packages/django/core/management/base.py", line 191, in run_from_argv [2010-07-22 17:10:01,365: WARNING/MainProcess] self.execute(*args, **options.__dict__) [2010-07-22 17:10:01,365: WARNING/MainProcess] File "/usr/local/lib/python2.6/site-packages/django/core/management/base.py", line 218, in execute [2010-07-22 17:10:01,365: WARNING/MainProcess] output = self.handle(*args, **options) [2010-07-22 17:10:01,365: WARNING/MainProcess] File "/usr/local/lib/python2.6/site-packages/django_celery-2.0.0-py2.6.egg/djcelery/management/commands/celeryd.py", line 22, in handle [2010-07-22 17:10:01,366: WARNING/MainProcess] run_worker(**options) [2010-07-22 17:10:01,366: WARNING/MainProcess] File "/usr/local/lib/python2.6/site-packages/celery-2.0.1-py2.6.egg/celery/bin/celeryd.py", line 385, in run_worker [2010-07-22 17:10:01,366: WARNING/MainProcess] return Worker(**options).run() [2010-07-22 17:10:01,366: WARNING/MainProcess] File "/usr/local/lib/python2.6/site-packages/celery-2.0.1-py2.6.egg/celery/bin/celeryd.py", line 218, in run [2010-07-22 17:10:01,366: WARNING/MainProcess] self.run_worker() [2010-07-22 17:10:01,366: WARNING/MainProcess] File "/usr/local/lib/python2.6/site-packages/celery-2.0.1-py2.6.egg/celery/bin/celeryd.py", line 312, in run_worker [2010-07-22 17:10:01,367: WARNING/MainProcess] worker.start() [2010-07-22 17:10:01,367: WARNING/MainProcess] File "/usr/local/lib/python2.6/site-packages/celery-2.0.1-py2.6.egg/celery/worker/__init__.py", line 206, in start [2010-07-22 17:10:01,367: WARNING/MainProcess] component.start() [2010-07-22 17:10:01,367: WARNING/MainProcess] File "/usr/local/lib/python2.6/site-packages/celery-2.0.1-py2.6.egg/celery/concurrency/processes/__init__.py", line 54, in start [2010-07-22 17:10:01,367: WARNING/MainProcess] maxtasksperchild=self.maxtasksperchild) [2010-07-22 17:10:01,367: WARNING/MainProcess] File "/usr/local/lib/python2.6/site-packages/celery-2.0.1-py2.6.egg/celery/concurrency/processes/pool.py", line 448, in __init__ [2010-07-22 17:10:01,368: WARNING/MainProcess] self._setup_queues() [2010-07-22 17:10:01,368: WARNING/MainProcess] File "/usr/local/lib/python2.6/site-packages/celery-2.0.1-py2.6.egg/celery/concurrency/processes/pool.py", line 564, in _setup_queues [2010-07-22 17:10:01,368: WARNING/MainProcess] self._inqueue = SimpleQueue() [2010-07-22 17:10:01,368: WARNING/MainProcess] File "/usr/local/lib/python2.6/multiprocessing/queues.py", line 315, in __init__ [2010-07-22 17:10:01,368: WARNING/MainProcess] self._rlock = Lock() [2010-07-22 17:10:01,368: WARNING/MainProcess] File "/usr/local/lib/python2.6/multiprocessing/synchronize.py", line 117, in __init__ [2010-07-22 17:10:01,369: WARNING/MainProcess] SemLock.__init__(self, SEMAPHORE, 1, 1) [2010-07-22 17:10:01,369: WARNING/MainProcess] File "/usr/local/lib/python2.6/multiprocessing/synchronize.py", line 49, in __init__ [2010-07-22 17:10:01,369: WARNING/MainProcess] sl = self._semlock = _multiprocessing.SemLock(kind, value, maxvalue) [2010-07-22 17:10:01,369: WARNING/MainProcess] OSError [2010-07-22 17:10:01,369: WARNING/MainProcess] : [2010-07-22 17:10:01,369: WARNING/MainProcess] [Errno 38] Function not implemented Am I just totally screwed and should use a new kernel that has this implemented or is there an easy way to resolve this?

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• What is Causing this IIS 7 Web Service Sporadic Connectivity Error?

  - by dpalau

  On sporadic occasions we receive the following error when attempting to call an .asmx web service from a .Net client application: "The underlying connection was closed: A connection that was expected to be kept alive was closed by the server. Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host." By sporadic I mean that it might occur zero, once every few days, or a half-dozen times a day for some users. It will never occur for the first web service call of a user. And the subsequent (usually the same) call will always work immediately after the failure. The failures happen across a variety of methods in the service and usually happens between 15-20 seconds (according to the log) from the time of the request. Looking in the IIS site log for the particular call will show one or the other of the following windows error codes: 121: The semaphore timeout period has elapsed. 1236: The network connection was aborted by the local system. Some additional environment details: Running on internal network web farm consisting of two servers running IIS7 on Windows Server 2008 OS. These problems did not occur when running in an older IIS6 web farm of three servers running on Windows Server 2003 (and we use a single IIS6/2003 instance for our development and staging environments with no issues). EDIT: Also, all of these server instances are VMWare virtual machines, not sure if that is a surprise anymore or not. The web service is a .Net 2.0/3.5 compiled .asmx web service that has its own application pool (.Net 2.0, integrated pipeline). Only has Windows Authentication enabled. We have another web service on the farm that uses the same physical path as the primary service, the only difference being that Basic Authentication is enabled. This is used for a portion of our ERP system. Have tried using the same and different application pool - no effect on the error. This site isn't hit as often as the primary site and has never had an error. As mentioned, the error will only happen when called from the .Net client - not from other applications. The client application is always creating a new web service object for each request and setting the service credentials to System.Net.CredentialCache.DefaultCredentials. The application is either deployed locally to a client or run in a Citrix server session. Those users running in Citrix doesn't seem to experience the issue, only locally deployed clients. The Citrix servers and the web farm are located in the same physical location and are located in the same IP range (10.67.xx.xx). Locally deployed clients experiencing the error are located elsewhere (10.105.xx.xx, 10.31.xx.xx). I've checked the OS logs to see if I can see any problems but nothing really sticks out. EDIT: Actually, I myself just ran into the error a little bit ago. I decided to check out the logs again and saw that there was a Security log entry of "Audit Failure" at the 'same' time (IIS log entry at 1:39:59, event log entry at 1:39:50). Not sure if this is a coincidence or not, I'll have to check out the logs of previous errors. I'm probably grasping for straws but the details: Log Name: Security Source: Microsoft-Windows-Security-Auditing Date: 7/8/2009 1:39:50 PM Event ID: 5159 Task Category: Filtering Platform Connection Level: Information Keywords: Audit Failure User: N/A Computer: is071019.<**.net Description: The Windows Filtering Platform has blocked a bind to a local port. Application Information: Process ID: 1260 Application Name: \device\harddiskvolume1\windows\system32\svchost.exe Network Information: Source Address: 0.0.0.0 Source Port: 54802 Protocol: 17 Filter Information: Filter Run-Time ID: 0 Layer Name: Resource Assignment Layer Run-Time ID: 36 I've also tried to use Failed Request Tracing in IIS7 but the service call never actually gets to where FRT can capture it (even though the failure is logged in the web service log). The network infrastructure group said they checked out the DNS and any NIC settings are correct so there is no 'flapping'. Everything pans out. I'm not sure that they checked out any domain controller servers though to see if that could be an issue. Any ideas? Or any other debugging strategies to get to the bottom of this? I'm just the developer in charge of the software and don't really have the knowledge on what to investigate from the networking side of things - although it does sound like a networking issue to me based on what is happening. Thanks in advance for any help.

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• NEC uPD720200 USB 3.0 not working on Ubuntu 12.04

  - by Jagged

  I've recently installed Ubuntu 12.04 64-bit on a HP Envy 15 1104tx. Most stuff appears to be working fine with the exception of the two USB3 ports (USB2 port works fine). I've read a lot of articles but so far have not been able to find a solution. I've tried adding 'pci=nomsi' to '/etc/default/grub' but this made no difference. Some articles suggest booting into Windows and upgrading the firmware on the uPD720200. Any body had any experience of this? Is there a way I can checked the firmware version of the NEC uPD720200 in Linux to see if there is an update available? Any help appreciated. uname -a: Linux HP-ENVY-15-1104tx 3.2.0-26-generic #41-Ubuntu SMP Thu Jun 14 17:49:24 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux lshw: hp-envy-15-1104tx description: Notebook product: HP ENVY 15 Notebook PC (WF591PA#ABG) vendor: Hewlett-Packard version: 0492110000241910001420000 serial: CNF0301C79 width: 64 bits capabilities: smbios-2.6 dmi-2.6 vsyscall32 configuration: boot=normal chassis=notebook family=103C_5335KV sku=WF591PA#ABG uuid=434E4630-3330-3143-3739-60EB6906688F *-core description: Motherboard product: 1522 vendor: Hewlett-Packard physical id: 0 version: 36.35 serial: CNF0301C79 slot: Base Board Chassis Location *-firmware description: BIOS vendor: Hewlett-Packard physical id: 0 version: F.2B date: 10/12/2010 size: 1MiB capacity: 1472KiB capabilities: pci upgrade shadowing cdboot bootselect edd int13floppynec int13floppytoshiba int13floppy360 int13floppy1200 int13floppy720 int13floppy2880 int9keyboard int10video acpi usb biosbootspecification *-memory description: System Memory physical id: 13 slot: System board or motherboard size: 16GiB *-bank:0 description: SODIMM DDR3 Synchronous 1333 MHz (0.8 ns) product: 9905428-043.A00LF physical id: 0 serial: E13C4316 slot: Bottom size: 4GiB width: 64 bits clock: 1333MHz (0.8ns) *-bank:1 description: SODIMM DDR3 Synchronous 1333 MHz (0.8 ns) product: 9905428-043.A00LF physical id: 1 serial: E03C3E16 slot: Bottom size: 4GiB width: 64 bits clock: 1333MHz (0.8ns) *-bank:2 description: SODIMM DDR3 Synchronous 1333 MHz (0.8 ns) product: 9905428-043.A00LF physical id: 2 serial: 672279CC slot: On Board size: 4GiB width: 64 bits clock: 1333MHz (0.8ns) *-bank:3 description: SODIMM DDR3 Synchronous 1333 MHz (0.8 ns) product: 9905428-043.A00LF physical id: 3 serial: 652286CC slot: On Board size: 4GiB width: 64 bits clock: 1333MHz (0.8ns) *-cpu description: CPU product: Intel(R) Core(TM) i7 CPU Q 820 @ 1.73GHz vendor: Intel Corp. physical id: 1d bus info: cpu@0 version: Intel(R) Core(TM) i7 CPU Q 820 @ 1.73GHz slot: CPU size: 1199MHz capacity: 1199MHz width: 64 bits clock: 1066MHz capabilities: x86-64 fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm sse4_1 sse4_2 popcnt lahf_lm ida tpr_shadow vnmi flexpriority ept vpid cpufreq configuration: cores=4 enabledcores=4 threads=8 *-cache:0 description: L3 cache physical id: 1e slot: L3 Cache size: 8MiB capacity: 8MiB capabilities: synchronous internal write-through unified *-cache:1 description: L2 cache physical id: 20 slot: L2 Cache size: 256KiB capacity: 256KiB capabilities: synchronous internal write-through unified *-cache:2 description: L1 cache physical id: 21 slot: L1 Cache size: 32KiB capacity: 32KiB capabilities: synchronous internal write-through instruction *-cache description: L1 cache physical id: 1f slot: L1 Cache size: 32KiB capacity: 32KiB capabilities: synchronous internal write-through data *-pci:0 description: Host bridge product: Core Processor DMI vendor: Intel Corporation physical id: 100 bus info: pci@0000:00:00.0 version: 11 width: 32 bits clock: 33MHz *-pci:0 description: PCI bridge product: Core Processor PCI Express Root Port 1 vendor: Intel Corporation physical id: 3 bus info: pci@0000:00:03.0 version: 11 width: 32 bits clock: 33MHz capabilities: pci msi pciexpress pm normal_decode bus_master cap_list configuration: driver=pcieport resources: irq:16 ioport:4000(size=4096) memory:d4100000-d41fffff ioport:c0000000(size=268435456) *-display description: VGA compatible controller product: Broadway PRO [Mobility Radeon HD 5800 Series] vendor: Hynix Semiconductor (Hyundai Electronics) physical id: 0 bus info: pci@0000:01:00.0 version: 00 width: 64 bits clock: 33MHz capabilities: pm pciexpress msi vga_controller bus_master cap_list rom configuration: driver=fglrx_pci latency=0 resources: irq:58 memory:c0000000-cfffffff memory:d4100000-d411ffff ioport:4000(size=256) memory:d4140000-d415ffff *-multimedia description: Audio device product: Juniper HDMI Audio [Radeon HD 5700 Series] vendor: Hynix Semiconductor (Hyundai Electronics) physical id: 0.1 bus info: pci@0000:01:00.1 version: 00 width: 64 bits clock: 33MHz capabilities: pm pciexpress msi bus_master cap_list configuration: driver=snd_hda_intel latency=0 resources: irq:56 memory:d4120000-d4123fff *-pci:1 description: PCI bridge product: Core Processor PCI Express Root Port 3 vendor: Intel Corporation physical id: 5 bus info: pci@0000:00:05.0 version: 11 width: 32 bits clock: 33MHz capabilities: pci msi pciexpress pm normal_decode bus_master cap_list configuration: driver=pcieport resources: irq:16 memory:d4000000-d40fffff *-usb description: USB controller product: uPD720200 USB 3.0 Host Controller vendor: NEC Corporation physical id: 0 bus info: pci@0000:02:00.0 version: 03 width: 64 bits clock: 33MHz capabilities: pm msi msix pciexpress xhci bus_master cap_list configuration: driver=xhci_hcd latency=0 resources: irq:16 memory:d4000000-d4001fff *-generic:0 UNCLAIMED description: System peripheral product: Core Processor System Management Registers vendor: Intel Corporation physical id: 8 bus info: pci@0000:00:08.0 version: 11 width: 32 bits clock: 33MHz capabilities: pciexpress cap_list configuration: latency=0 *-generic:1 UNCLAIMED description: System peripheral product: Core Processor Semaphore and Scratchpad Registers vendor: Intel Corporation physical id: 8.1 bus info: pci@0000:00:08.1 version: 11 width: 32 bits clock: 33MHz capabilities: pciexpress cap_list configuration: latency=0 *-generic:2 UNCLAIMED description: System peripheral product: Core Processor System Control and Status Registers vendor: Intel Corporation physical id: 8.2 bus info: pci@0000:00:08.2 version: 11 width: 32 bits clock: 33MHz capabilities: pciexpress cap_list configuration: latency=0 *-generic:3 UNCLAIMED description: System peripheral product: Core Processor Miscellaneous Registers vendor: Intel Corporation physical id: 8.3 bus info: pci@0000:00:08.3 version: 11 width: 32 bits clock: 33MHz configuration: latency=0 *-generic:4 UNCLAIMED description: System peripheral product: Core Processor QPI Link vendor: Intel Corporation physical id: 10 bus info: pci@0000:00:10.0 version: 11 width: 32 bits clock: 33MHz configuration: latency=0 *-generic:5 UNCLAIMED description: System peripheral product: Core Processor QPI Routing and Protocol Registers vendor: Intel Corporation physical id: 10.1 bus info: pci@0000:00:10.1 version: 11 width: 32 bits clock: 33MHz configuration: latency=0 *-multimedia description: Audio device product: 5 Series/3400 Series Chipset High Definition Audio vendor: Intel Corporation physical id: 1b bus info: pci@0000:00:1b.0 version: 05 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list configuration: driver=snd_hda_intel latency=0 resources: irq:55 memory:d4200000-d4203fff *-pci:2 description: PCI bridge product: 5 Series/3400 Series Chipset PCI Express Root Port 1 vendor: Intel Corporation physical id: 1c bus info: pci@0000:00:1c.0 version: 05 width: 32 bits clock: 33MHz capabilities: pci pciexpress msi pm normal_decode bus_master cap_list configuration: driver=pcieport resources: irq:17 ioport:3000(size=4096) memory:d3000000-d3ffffff ioport:d0000000(size=16777216) *-network description: Wireless interface product: Centrino Advanced-N 6200 vendor: Intel Corporation physical id: 0 bus info: pci@0000:03:00.0 logical name: wlan0 version: 35 serial: 00:27:10:40:e4:68 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=iwlwifi driverversion=3.2.0-26-generic firmware=9.221.4.1 build 25532 latency=0 link=no multicast=yes wireless=IEEE 802.11abgn resources: irq:54 memory:d3000000-d3001fff *-pci:3 description: PCI bridge product: 5 Series/3400 Series Chipset PCI Express Root Port 2 vendor: Intel Corporation physical id: 1c.1 bus info: pci@0000:00:1c.1 version: 05 width: 32 bits clock: 33MHz capabilities: pci pciexpress msi pm normal_decode bus_master cap_list configuration: driver=pcieport resources: irq:16 ioport:2000(size=4096) memory:d2000000-d2ffffff ioport:d1000000(size=16777216) *-network description: Ethernet interface product: AR8131 Gigabit Ethernet vendor: Atheros Communications Inc. physical id: 0 bus info: pci@0000:04:00.0 logical name: eth0 version: c0 serial: 60:eb:69:06:68:8f size: 1Gbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress vpd bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=atl1c driverversion=1.0.1.0-NAPI duplex=full firmware=N/A ip=10.161.0.147 latency=0 link=yes multicast=yes port=twisted pair speed=1Gbit/s resources: irq:57 memory:d2000000-d203ffff ioport:2000(size=128) *-usb description: USB controller product: 5 Series/3400 Series Chipset USB2 Enhanced Host Controller vendor: Intel Corporation physical id: 1d bus info: pci@0000:00:1d.0 version: 05 width: 32 bits clock: 33MHz capabilities: pm debug ehci bus_master cap_list configuration: driver=ehci_hcd latency=0 resources: irq:20 memory:d4205800-d4205bff *-pci:4 description: PCI bridge product: 82801 Mobile PCI Bridge vendor: Intel Corporation physical id: 1e bus info: pci@0000:00:1e.0 version: a5 width: 32 bits clock: 33MHz capabilities: pci subtractive_decode bus_master cap_list *-isa description: ISA bridge product: Mobile 5 Series Chipset LPC Interface Controller vendor: Intel Corporation physical id: 1f bus info: pci@0000:00:1f.0 version: 05 width: 32 bits clock: 33MHz capabilities: isa bus_master cap_list configuration: latency=0 *-storage description: RAID bus controller product: 82801 Mobile SATA Controller [RAID mode] vendor: Intel Corporation physical id: 1f.2 bus info: pci@0000:00:1f.2 logical name: scsi0 version: 05 width: 32 bits clock: 66MHz capabilities: storage msi pm bus_master cap_list emulated configuration: driver=ahci latency=0 resources: irq:45 ioport:5048(size=8) ioport:5054(size=4) ioport:5040(size=8) ioport:5050(size=4) ioport:5020(size=32) memory:d4205000-d42057ff *-disk description: ATA Disk product: OCZ-VERTEX3 physical id: 0.0.0 bus info: scsi@0:0.0.0 logical name: /dev/sda version: 2.15 serial: OCZ-0350P6H316X5KUQE size: 223GiB (240GB) capabilities: partitioned partitioned:dos configuration: ansiversion=5 signature=000592dd *-volume:0 description: EXT4 volume vendor: Linux physical id: 1 bus info: scsi@0:0.0.0,1 logical name: /dev/sda1 logical name: / version: 1.0 serial: e741f18c-cfc5-4bce-b1e7-f80e517a3a22 size: 207GiB capacity: 207GiB capabilities: primary bootable journaled extended_attributes large_files huge_files dir_nlink recover extents ext4 ext2 initialized configuration: created=2012-06-15 06:49:27 filesystem=ext4 lastmountpoint=/ modified=2012-06-14 21:23:42 mount.fstype=ext4 mount.options=rw,relatime,errors=remount-ro,user_xattr,barrier=1,data=ordered mounted=2012-07-10 16:18:20 state=mounted *-volume:1 description: Extended partition physical id: 2 bus info: scsi@0:0.0.0,2 logical name: /dev/sda2 size: 15GiB capacity: 15GiB capabilities: primary extended partitioned partitioned:extended *-logicalvolume description: Linux swap / Solaris partition physical id: 5 logical name: /dev/sda5 capacity: 15GiB capabilities: nofs *-serial UNCLAIMED description: SMBus product: 5 Series/3400 Series Chipset SMBus Controller vendor: Intel Corporation physical id: 1f.3 bus info: pci@0000:00:1f.3 version: 05 width: 64 bits clock: 33MHz configuration: latency=0 resources: memory:d4205c00-d4205cff ioport:5000(size=32) *-pci:1 description: Host bridge product: Core Processor QuickPath Architecture Generic Non-Core Registers vendor: Intel Corporation physical id: 101 bus info: pci@0000:ff:00.0 version: 04 width: 32 bits clock: 33MHz *-pci:2 description: Host bridge product: Core Processor QuickPath Architecture System Address Decoder vendor: Intel Corporation physical id: 102 bus info: pci@0000:ff:00.1 version: 04 width: 32 bits clock: 33MHz *-pci:3 description: Host bridge product: Core Processor QPI Link 0 vendor: Intel Corporation physical id: 103 bus info: pci@0000:ff:02.0 version: 04 width: 32 bits clock: 33MHz *-pci:4 description: Host bridge product: Core Processor QPI Physical 0 vendor: Intel Corporation physical id: 104 bus info: pci@0000:ff:02.1 version: 04 width: 32 bits clock: 33MHz *-pci:5 description: Host bridge product: Core Processor Integrated Memory Controller vendor: Intel Corporation physical id: 105 bus info: pci@0000:ff:03.0 version: 04 width: 32 bits clock: 33MHz *-pci:6 description: Host bridge product: Core Processor Integrated Memory Controller Target Address Decoder vendor: Intel Corporation physical id: 106 bus info: pci@0000:ff:03.1 version: 04 width: 32 bits clock: 33MHz *-pci:7 description: Host bridge product: Core Processor Integrated Memory Controller Test Registers vendor: Intel Corporation physical id: 107 bus info: pci@0000:ff:03.4 version: 04 width: 32 bits clock: 33MHz *-pci:8 description: Host bridge product: Core Processor Integrated Memory Controller Channel 0 Control Registers vendor: Intel Corporation physical id: 108 bus info: pci@0000:ff:04.0 version: 04 width: 32 bits clock: 33MHz *-pci:9 description: Host bridge product: Core Processor Integrated Memory Controller Channel 0 Address Registers vendor: Intel Corporation physical id: 109 bus info: pci@0000:ff:04.1 version: 04 width: 32 bits clock: 33MHz *-pci:10 description: Host bridge product: Core Processor Integrated Memory Controller Channel 0 Rank Registers vendor: Intel Corporation physical id: 10a bus info: pci@0000:ff:04.2 version: 04 width: 32 bits clock: 33MHz *-pci:11 description: Host bridge product: Core Processor Integrated Memory Controller Channel 0 Thermal Control Registers vendor: Intel Corporation physical id: 10b bus info: pci@0000:ff:04.3 version: 04 width: 32 bits clock: 33MHz *-pci:12 description: Host bridge product: Core Processor Integrated Memory Controller Channel 1 Control Registers vendor: Intel Corporation physical id: 10c bus info: pci@0000:ff:05.0 version: 04 width: 32 bits clock: 33MHz *-pci:13 description: Host bridge product: Core Processor Integrated Memory Controller Channel 1 Address Registers vendor: Intel Corporation physical id: 10d bus info: pci@0000:ff:05.1 version: 04 width: 32 bits clock: 33MHz *-pci:14 description: Host bridge product: Core Processor Integrated Memory Controller Channel 1 Rank Registers vendor: Intel Corporation physical id: 10e bus info: pci@0000:ff:05.2 version: 04 width: 32 bits clock: 33MHz *-pci:15 description: Host bridge product: Core Processor Integrated Memory Controller Channel 1 Thermal Control Registers vendor: Intel Corporation physical id: 10f bus info: pci@0000:ff:05.3 version: 04 width: 32 bits clock: 33MHz *-battery description: Lithium Ion Battery product: NK06053 vendor: SMP-ATL24 physical id: 1 slot: Primary capacity: 4800mWh configuration: voltage=11.1V lspci: 02:00.0 USB controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 03) (prog-if 30 [XHCI]) Subsystem: Hewlett-Packard Company Device 1522 Flags: bus master, fast devsel, latency 0, IRQ 16 Memory at d4000000 (64-bit, non-prefetchable) [size=8K] Capabilities: [50] Power Management version 3 Capabilities: [70] MSI: Enable- Count=1/8 Maskable- 64bit+ Capabilities: [90] MSI-X: Enable+ Count=8 Masked- Capabilities: [a0] Express Endpoint, MSI 00 Capabilities: [100] Advanced Error Reporting Capabilities: [140] Device Serial Number ff-ff-ff-ff-ff-ff-ff-ff Capabilities: [150] Latency Tolerance Reporting Kernel driver in use: xhci_hcd lsusb (with thumb drive plugged into USB3 port): Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 003 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub Bus 001 Device 003: ID 5986:01d0 Acer, Inc Bus 001 Device 004: ID 03f0:231d Hewlett-Packard

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• Thread scheduling Round Robin / scheduling dispatch

  - by MRP

  #include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <semaphore.h> #define NUM_THREADS 4 #define COUNT_LIMIT 13 int done = 0; int count = 0; int quantum = 2; int thread_ids[4] = {0,1,2,3}; int thread_runtime[4] = {0,5,4,7}; pthread_mutex_t count_mutex; pthread_cond_t count_threshold_cv; void * inc_count(void * arg); static sem_t count_sem; int quit = 0; ///////// Inc_Count//////////////// void *inc_count(void *t) { long my_id = (long)t; int i; sem_wait(&count_sem); /////////////CRIT SECTION////////////////////////////////// printf("run_thread = %d\n",my_id); printf("%d \n",thread_runtime[my_id]); for( i=0; i < thread_runtime[my_id];i++) { printf("runtime= %d\n",thread_runtime[my_id]); pthread_mutex_lock(&count_mutex); count++; if (count == COUNT_LIMIT) { pthread_cond_signal(&count_threshold_cv); printf("inc_count(): thread %ld, count = %d Threshold reached.\n", my_id, count); } printf("inc_count(): thread %ld, count = %d, unlocking mutex\n",my_id, count); pthread_mutex_unlock(&count_mutex); sleep(1) ; }//End For sem_post(&count_sem); // Next Thread Enters Crit Section pthread_exit(NULL); } /////////// Count_Watch //////////////// void *watch_count(void *t) { long my_id = (long)t; printf("Starting watch_count(): thread %ld\n", my_id); pthread_mutex_lock(&count_mutex); if (count<COUNT_LIMIT) { pthread_cond_wait(&count_threshold_cv, &count_mutex); printf("watch_count(): thread %ld Condition signal received.\n", my_id); printf("watch_count(): thread %ld count now = %d.\n", my_id, count); } pthread_mutex_unlock(&count_mutex); pthread_exit(NULL); } ////////////////// Main //////////////// int main (int argc, char *argv[]) { int i; long t1=0, t2=1, t3=2, t4=3; pthread_t threads[4]; pthread_attr_t attr; sem_init(&count_sem, 0, 1); /* Initialize mutex and condition variable objects */ pthread_mutex_init(&count_mutex, NULL); pthread_cond_init (&count_threshold_cv, NULL); /* For portability, explicitly create threads in a joinable state */ pthread_attr_init(&attr); pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE); pthread_create(&threads[0], &attr, watch_count, (void *)t1); pthread_create(&threads[1], &attr, inc_count, (void *)t2); pthread_create(&threads[2], &attr, inc_count, (void *)t3); pthread_create(&threads[3], &attr, inc_count, (void *)t4); /* Wait for all threads to complete */ for (i=0; i<NUM_THREADS; i++) { pthread_join(threads[i], NULL); } printf ("Main(): Waited on %d threads. Done.\n", NUM_THREADS); /* Clean up and exit */ pthread_attr_destroy(&attr); pthread_mutex_destroy(&count_mutex); pthread_cond_destroy(&count_threshold_cv); pthread_exit(NULL); } I am trying to learn thread scheduling, there is a lot of technical coding that I don't know. I do know in theory how it should work, but having trouble getting started in code... I know, at least I think, this program is not real time and its not meant to be. Some how I need to create a scheduler dispatch to control the threads in the order they should run... RR FCFS SJF ect. Right now I don't have a dispatcher. What I do have is semaphores/ mutex to control the threads. This code does run FCFS... and I have been trying to use semaphores to create a RR.. but having a lot of trouble. I believe it would be easier to create a dispatcher but I dont know how. I need help, I am not looking for answers just direction.. some sample code will help to understand a bit more. Thank you.

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• Techniques for modeling a dynamic dataflow with Java concurrency API

  - by Maian

  Is there an elegant way to model a dynamic dataflow in Java? By dataflow, I mean there are various types of tasks, and these tasks can be "connected" arbitrarily, such that when a task finishes, successor tasks are executed in parallel using the finished tasks output as input, or when multiple tasks finish, their output is aggregated in a successor task (see flow-based programming). By dynamic, I mean that the type and number of successors tasks when a task finishes depends on the output of that finished task, so for example, task A may spawn task B if it has a certain output, but may spawn task C if has a different output. Another way of putting it is that each task (or set of tasks) is responsible for determining what the next tasks are. Sample dataflow for rendering a webpage: I have as task types: file downloader, HTML/CSS renderer, HTML parser/DOM builder, image renderer, JavaScript parser, JavaScript interpreter. File downloader task for HTML file HTML parser/DOM builder task File downloader task for each embedded file/link If image, image renderer If external JavaScript, JavaScript parser JavaScript interpreter Otherwise, just store in some var/field in HTML parser task JavaScript parser for each embedded script JavaScript interpreter Wait for above tasks to finish, then HTML/CSS renderer (obviously not optimal or perfectly correct, but this is simple) I'm not saying the solution needs to be some comprehensive framework (in fact, the closer to the JDK API, the better), and I absolutely don't want something as heavyweight is say Spring Web Flow or some declarative markup or other DSL. To be more specific, I'm trying to think of a good way to model this in Java with Callables, Executors, ExecutorCompletionServices, and perhaps various synchronizer classes (like Semaphore or CountDownLatch). There are a couple use cases and requirements: Don't make any assumptions on what executor(s) the tasks will run on. In fact, to simplify, just assume there's only one executor. It can be a fixed thread pool executor, so a naive implementation can result in deadlocks (e.g. imagine a task that submits another task and then blocks until that subtask is finished, and now imagine several of these tasks using up all the threads). To simplify, assume that the data is not streamed between tasks (task output-succeeding task input) - the finishing task and succeeding task won't exist together, so the input data to the succeeding task will not be changed by the preceeding task (since it's already done). There are only a couple operations that the dataflow "engine" should be able to handle: A mechanism where a task can queue more tasks A mechanism whereby a successor task is not queued until all the required input tasks are finished A mechanism whereby the main thread (or other threads not managed by the executor) blocks until the flow is finished A mechanism whereby the main thread (or other threads not managed by the executor) blocks until certain tasks have finished Since the dataflow is dynamic (depends on input/state of the task), the activation of these mechanisms should occur within the task code, e.g. the code in a Callable is itself responsible for queueing more Callables. The dataflow "internals" should not be exposed to the tasks (Callables) themselves - only the operations listed above should be available to the task. Note that the type of the data is not necessarily the same for all tasks, e.g. a file download task may accept a File as input but will output a String. If a task throws an uncaught exception (indicating some fatal error requiring all dataflow processing to stop), it must propagate up to the thread that initiated the dataflow as quickly as possible and cancel all tasks (or something fancier like a fatal error handler). Tasks should be launched as soon as possible. This along with the previous requirement should preclude simple Future polling + Thread.sleep(). As a bonus, I would like to dataflow engine itself to perform some action (like logging) every time task is finished or when no has finished in X time since last task has finished. Something like: ExecutorCompletionService<T> ecs; while (hasTasks()) { Future<T> future = ecs.poll(1 minute); some_action_like_logging(); if (future != null) { future.get() ... } ... } Are there straightforward ways to do all this with Java concurrency API? Or if it's going to complex no matter what with what's available in the JDK, is there a lightweight library that satisfies the requirements? I already have a partial solution that fits my particular use case (it cheats in a way, since I'm using two executors, and just so you know, it's not related at all to the web browser example I gave above), but I'd like to see a more general purpose and elegant solution.

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• Unknown error in Producer/Consumer program, believe it to be an infinite loop.

  - by ray2k

  Hello, I am writing a program that is solving the producer/consumer problem, specifically the bounded-buffer version(i believe they mean the same thing). The producer will be generating x number of random numbers, where x is a command line parameter to my program. At the current moment, I believe my program is entering an infinite loop, but I'm not sure why it is occurring. I believe I am executing the semaphores correctly. You compile it like this: gcc -o prodcon prodcon.cpp -lpthread -lrt Then to run, ./prodcon 100(the number of randum nums to produce) This is my code. typedef int buffer_item; #include <stdlib.h> #include <stdio.h> #include <pthread.h> #include <semaphore.h> #include <unistd.h> #define BUFF_SIZE 10 #define RAND_DIVISOR 100000000 #define TRUE 1 //two threads void *Producer(void *param); void *Consumer(void *param); int insert_item(buffer_item item); int remove_item(buffer_item *item); int returnRandom(); //the global semaphores sem_t empty, full, mutex; //the buffer buffer_item buf[BUFF_SIZE]; //buffer counter int counter; //number of random numbers to produce int numRand; int main(int argc, char** argv) { /* thread ids and attributes */ pthread_t pid, cid; pthread_attr_t attr; pthread_attr_init(&attr); pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM); numRand = atoi(argv[1]); sem_init(&empty,0,BUFF_SIZE); sem_init(&full,0,0); sem_init(&mutex,0,0); printf("main started\n"); pthread_create(&pid, &attr, Producer, NULL); pthread_create(&cid, &attr, Consumer, NULL); printf("main gets here"); pthread_join(pid, NULL); pthread_join(cid, NULL); printf("main done\n"); return 0; } //generates a randum number between 1 and 100 int returnRandom() { int num; srand(time(NULL)); num = rand() % 100 + 1; return num; } //begin producing items void *Producer(void *param) { buffer_item item; int i; for(i = 0; i < numRand; i++) { //sleep for a random period of time int rNum = rand() / RAND_DIVISOR; sleep(rNum); //generate a random number item = returnRandom(); //acquire the empty lock sem_wait(&empty); //acquire the mutex lock sem_wait(&mutex); if(insert_item(item)) { fprintf(stderr, " Producer report error condition\n"); } else { printf("producer produced %d\n", item); } /* release the mutex lock */ sem_post(&mutex); /* signal full */ sem_post(&full); } return NULL; } /* Consumer Thread */ void *Consumer(void *param) { buffer_item item; int i; for(i = 0; i < numRand; i++) { /* sleep for a random period of time */ int rNum = rand() / RAND_DIVISOR; sleep(rNum); /* aquire the full lock */ sem_wait(&full); /* aquire the mutex lock */ sem_wait(&mutex); if(remove_item(&item)) { fprintf(stderr, "Consumer report error condition\n"); } else { printf("consumer consumed %d\n", item); } /* release the mutex lock */ sem_post(&mutex); /* signal empty */ sem_post(&empty); } return NULL; } /* Add an item to the buffer */ int insert_item(buffer_item item) { /* When the buffer is not full add the item and increment the counter*/ if(counter < BUFF_SIZE) { buf[counter] = item; counter++; return 0; } else { /* Error the buffer is full */ return -1; } } /* Remove an item from the buffer */ int remove_item(buffer_item *item) { /* When the buffer is not empty remove the item and decrement the counter */ if(counter > 0) { *item = buf[(counter-1)]; counter--; return 0; } else { /* Error buffer empty */ return -1; } }

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• Saving in mongoDb with Mongoose, unexpected elements saved

  - by guiomie

  When I write in my mongoDB with mongoose the operation is treated with success, my document is saved, but there is also all kind of weird other sutff written down. It seems to be mongoose code. What could cause this? I add stuff in a specific array with: resultReference.ref[arrayLocation].allEvents.push(theEvent); {id: 11, allEvents: [] } is the structure of a ref element, and I push theEvent in the allEvents array. I then resultReference.save() I use express, mongoose and mongoHQ for database. I tried on a local mongo server, and this annoyance is still there. I've print in my console the document to write before save() and non of this weird code is there. { id 11 allEvents [ 0 { _events { maxListeners 0 } _doc { _id {"$oid": "4eb87834f54944e263000003"} title "Test" allDay false start 2011-11-10 13:00:00 UTC end 2011-11-10 15:00:00 UTC url "/test/4eb87834f54944e263000002" color "#99CCFF" ref "4eb87834f54944e263000002" } _activePaths { paths { title "modify" allDay "modify" start "modify" end "modify" url "modify" color "modify" ref "modify" } states { init { } modify { title true allDay true start true end true url true color true ref true } require { } } stateNames [ 0 "require" 1 "modify" 2 "init" ] } _saveError null _validationError null isNew true _pres { save [ 0 function (next) { // we keep the error semaphore to make sure we don't // call `save` unnecessarily (we only need 1 error) var subdocs = 0 , error = false , self = this; var arrays = this._activePaths .map('init', 'modify', function (i) { return self.getValue(i); }) .filter(function (val) { return (val && val instanceof DocumentArray && val.length); }); if (!arrays.length) return next(); arrays.forEach(function (array) { subdocs += array.length; array.forEach(function (value) { if (!error) value.save(function (err) { if (!error) { if (err) { error = true; next(err); } else --subdocs || next(); } }); }); }); } 1 "function checkForExistingErrors(next) { if (self._saveError){ next(self._saveError); self._saveError = null; } else { next(); } }" 2 "function validation(next) { return self.validate.call(self, next); }" ] } _posts { save [ ] } save function () { var self = this , hookArgs // arguments eventually passed to the hook - are mutable , lastArg = arguments[arguments.length-1] , pres = this._pres[name] , posts = this._posts[name] , _total = pres.length , _current = -1 , _asyncsLeft = proto[name].numAsyncPres , _next = function () { if (arguments[0] instanceof Error) { return handleError(arguments[0]); } var _args = Array.prototype.slice.call(arguments) , currPre , preArgs; if (_args.length && !(arguments[0] === null && typeof lastArg === 'function')) hookArgs = _args; if (++_current < _total) { currPre = pres[_current] if (currPre.isAsync && currPre.length < 2) throw new Error("Your pre must have next and done arguments -- e.g., function (next, done, ...)"); if (currPre.length < 1) throw new Error("Your pre must have a next argument -- e.g., function (next, ...)"); preArgs = (currPre.isAsync ? [once(_next), once(_asyncsDone)] : [once(_next)]).concat(hookArgs); return currPre.apply(self, preArgs); } else if (!proto[name].numAsyncPres) { return _done.apply(self, hookArgs); } } , _done = function () { var args_ = Array.prototype.slice.call(arguments) , ret, total_, current_, next_, done_, postArgs; if (_current === _total) { ret = fn.apply(self, args_); total_ = posts.length; current_ = -1; next_ = function () { if (arguments[0] instanceof Error) { return handleError(arguments[0]); } var args_ = Array.prototype.slice.call(arguments, 1) , currPost , postArgs; if (args_.length) hookArgs = args_; if (++current_ < total_) { currPost = posts[current_] if (currPost.length < 1) throw new Error("Your post must have a next argument -- e.g., function (next, ...)"); postArgs = [once(next_)].concat(hookArgs); return currPost.apply(self, postArgs); } }; if (total_) return next_(); return ret; } }; if (_asyncsLeft) { function _asyncsDone (err) { if (err && err instanceof Error) { return handleError(err); } --_asyncsLeft || _done.apply(self, hookArgs); } } function handleError (err) { if ('function' == typeof lastArg) return lastArg(err); if (errorCb) return errorCb.call(self, err); throw err; } return _next.apply(this, arguments); } errors null } ] } ]

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• Microbenchmark showing process-switching faster than thread-switching; what's wrong?

  - by Yang

  I have two simple microbenchmarks trying to measure thread- and process-switching overheads, but the process-switching overhead. The code is living here, and r1667 is pasted below: https://assorted.svn.sourceforge.net/svnroot/assorted/sandbox/trunk/src/c/process_switch_bench.c // on zs, ~2.1-2.4us/switch #include <stdlib.h> #include <fcntl.h> #include <stdint.h> #include <stdio.h> #include <semaphore.h> #include <unistd.h> #include <sys/wait.h> #include <sys/types.h> #include <sys/time.h> #include <pthread.h> uint32_t COUNTER; pthread_mutex_t LOCK; pthread_mutex_t START; sem_t *s0, *s1, *s2; void * threads ( void * unused ) { // Wait till we may fire away sem_wait(s2); for (;;) { pthread_mutex_lock(&LOCK); pthread_mutex_unlock(&LOCK); COUNTER++; sem_post(s0); sem_wait(s1); } return 0; } int64_t timeInMS () { struct timeval t; gettimeofday(&t, NULL); return ( (int64_t)t.tv_sec * 1000 + (int64_t)t.tv_usec / 1000 ); } int main ( int argc, char ** argv ) { int64_t start; pthread_t t1; pthread_mutex_init(&LOCK, NULL); COUNTER = 0; s0 = sem_open("/s0", O_CREAT, 0022, 0); if (s0 == 0) { perror("sem_open"); exit(1); } s1 = sem_open("/s1", O_CREAT, 0022, 0); if (s1 == 0) { perror("sem_open"); exit(1); } s2 = sem_open("/s2", O_CREAT, 0022, 0); if (s2 == 0) { perror("sem_open"); exit(1); } int x, y, z; sem_getvalue(s0, &x); sem_getvalue(s1, &y); sem_getvalue(s2, &z); printf("%d %d %d\n", x, y, z); pid_t pid = fork(); if (pid) { pthread_create(&t1, NULL, threads, NULL); pthread_detach(t1); // Get start time and fire away start = timeInMS(); sem_post(s2); sem_post(s2); // Wait for about a second sleep(1); // Stop thread pthread_mutex_lock(&LOCK); // Find out how much time has really passed. sleep won't guarantee me that // I sleep exactly one second, I might sleep longer since even after being // woken up, it can take some time before I gain back CPU time. Further // some more time might have passed before I obtained the lock! int64_t time = timeInMS() - start; // Correct the number of thread switches accordingly COUNTER = (uint32_t)(((uint64_t)COUNTER * 2 * 1000) / time); printf("Number of process switches in about one second was %u\n", COUNTER); printf("roughly %f microseconds per switch\n", 1000000.0 / COUNTER); // clean up kill(pid, 9); wait(0); sem_close(s0); sem_close(s1); sem_unlink("/s0"); sem_unlink("/s1"); sem_unlink("/s2"); } else { if (1) { sem_t *t = s0; s0 = s1; s1 = t; } threads(0); // never return } return 0; } https://assorted.svn.sourceforge.net/svnroot/assorted/sandbox/trunk/src/c/thread_switch_bench.c // From <http://stackoverflow.com/questions/304752/how-to-estimate-the-thread-context-switching-overhead> // on zs, ~4-5us/switch; tried making COUNTER updated only by one thread, but no difference #include <stdlib.h> #include <stdint.h> #include <stdio.h> #include <pthread.h> #include <unistd.h> #include <sys/time.h> uint32_t COUNTER; pthread_mutex_t LOCK; pthread_mutex_t START; pthread_cond_t CONDITION; void * threads ( void * unused ) { // Wait till we may fire away pthread_mutex_lock(&START); pthread_mutex_unlock(&START); int first=1; pthread_mutex_lock(&LOCK); // If I'm not the first thread, the other thread is already waiting on // the condition, thus Ihave to wake it up first, otherwise we'll deadlock if (COUNTER > 0) { pthread_cond_signal(&CONDITION); first=0; } for (;;) { if (first) COUNTER++; pthread_cond_wait(&CONDITION, &LOCK); // Always wake up the other thread before processing. The other // thread will not be able to do anything as long as I don't go // back to sleep first. pthread_cond_signal(&CONDITION); } pthread_mutex_unlock(&LOCK); return 0; } int64_t timeInMS () { struct timeval t; gettimeofday(&t, NULL); return ( (int64_t)t.tv_sec * 1000 + (int64_t)t.tv_usec / 1000 ); } int main ( int argc, char ** argv ) { int64_t start; pthread_t t1; pthread_t t2; pthread_mutex_init(&LOCK, NULL); pthread_mutex_init(&START, NULL); pthread_cond_init(&CONDITION, NULL); pthread_mutex_lock(&START); COUNTER = 0; pthread_create(&t1, NULL, threads, NULL); pthread_create(&t2, NULL, threads, NULL); pthread_detach(t1); pthread_detach(t2); // Get start time and fire away start = timeInMS(); pthread_mutex_unlock(&START); // Wait for about a second sleep(1); // Stop both threads pthread_mutex_lock(&LOCK); // Find out how much time has really passed. sleep won't guarantee me that // I sleep exactly one second, I might sleep longer since even after being // woken up, it can take some time before I gain back CPU time. Further // some more time might have passed before I obtained the lock! int64_t time = timeInMS() - start; // Correct the number of thread switches accordingly COUNTER = (uint32_t)(((uint64_t)COUNTER * 2 * 1000) / time); printf("Number of thread switches in about one second was %u\n", COUNTER); printf("roughly %f microseconds per switch\n", 1000000.0 / COUNTER); return 0; }

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