thread-safety

问题 StringBuffer is synchronized but StringBuilder is not ! This has been discussed deeply at Difference between StringBuilder and StringBuffer. There is an example code there (Answered by @NicolasZozol), which address two issues: compares the performance of these StringBuffer and StringBuilder shows the StringBuilder could fail in a multithread environment. My question is about second part , exactly what makes it to go wrong?! When you run the code some times, the stack trace is displayed as

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 5 years ago . Basically, I got burnt by EventMachine which claimed JRuby compatibility but the java implementation failed on thread safety issues in standard patterns ( Thread.new{EM.run} doesn't work under JRuby for example) - we're talking pretty basic EM functions here. Unfortunately, most

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 5 years ago . Basically, I got burnt by EventMachine which claimed JRuby compatibility but the java implementation failed on thread safety issues in standard patterns ( Thread.new{EM.run} doesn't work under JRuby for example) - we're talking pretty basic EM functions here. Unfortunately, most

问题 In a ASP.Net web application, when you have a stack intensive operation to run, a stackoverflow exception is thrown on IIS when the stack size crosses the IIS set limit of 256K. A regular winform application however has a limit of 1MB. So the exception would not occur when running the same operation in a Winform application. There is no recursion or any other code specific issues here. There are ways to work around the problem like using EditBin on w3wp.exe, but it’s not supported. Other

问题 SSL Documentation Analaysis This question is pertaining the usage of the HMAC routines in OpenSSL. Since Openssl documentation is a tad on the weak side in certain areas, profiling has revealed that using the: unsigned char *HMAC(const EVP_MD *evp_md, const void *key, int key_len, const unsigned char *d, int n, unsigned char *md, unsigned int *md_len); From here, shows 40% of my library runtime is devoted to creating and taking down HMAC_CTX 's behind the scenes. There are also two additional

问题 I have a race condition with the following code if two requests come in really close together in an ASP.NET MVC app: var workload = org.Workloads.SingleOrDefault(p => ...conditions...); if (workload == null) { workload = org.CreateWorkload(id); } workload and org are EntityFramework objects. The call to CreateWorkload adds a row to a Workloads table in the database. ( We really should enforce this with a UNIQUE constraint on the table, but I can't now that the table has some dirty data in it.

问题 I'm working on some code that has a global array that can be accessed by two threads for reading writing purposes. There will be no batch processing where a range of indexes are read or written, so I'm trying to figure out if I should lock the entire array or only the array index I am currently using. The easiest solution would be to consider the array a CS and put a big fat lock around it, but can I avoid this and just lock an index? Cheers. 回答1: Locking one index implies that you can keep

问题 I'm trying to design a message queue for an object. There is a set of X threads that can all send message (to be processed later) to this object. If I have a std::map<thread_id_t, message> , is this thread safe, assuming thread one only adds messages with a key of 1, thread 2 to key 2, etc..? 回答1: std::map is not thread safe for multiple simultaneous writers. One of the many reasons why STL maps are not thread safe is that the underlying implementation of an STL map is an AVL tree that needs

问题 Recently I've started using threading.local() as way for some apis to store and access state for duration of request without having to access request object. So lets say I have certain code: _thread_local = threading.local() _thread_local.theme = 'darkblues' How long does that _thread_local.theme variable lasts? Do I have to manually unset it at the end of request in, say, custom middleware? Or it's deleted by Django automatically after it finishes processing request? 回答1: It will last as

问题 The scenario I am facing is as below. Because ThreadPool is 1 instance per process so my question is that would method 1 cancel tasks queued by method 2 after 3 seconds ? http request comes in *method 1 gets executed first*: ThreadPool.QueueUserWorkItem x 3 WaitHandle.WaitAll for 3 seconds *method 2 gets executed after method 1*: ThreadPool.QueueUserWorkItem x 10 WaitHandle.WaitAll for 10 seconds Sorry I think I totally misunderstood the use of WaitHandle. It seems that if I do below