thread-local

问题 [ThreadStatic] is defined using attribute while ThreadLocal<T> uses generic. Why different design solutions were chosen? What are the advantages and disadvantages of using generic over attributes in this case? 回答1: Something the blog post noted in the comments doesn't make explicit, but I find to be very important, is that [ThreadStatic] doesn't automatically initialize things for every thread. For example, say you have this: [ThreadStatic] private static int Foo = 42; The first thread that

问题 How is ThreadLocal implemented? Is it implemented in Java (using some concurrent map from ThreadID to object), or does it use some JVM hook to do it more efficiently? 回答1: All of the answers here are correct, but a little disappointing as they somewhat gloss over how clever ThreadLocal 's implementation is. I was just looking at the source code for ThreadLocal and was pleasantly impressed by how it's implemented. The Naive Implementation If I asked you to implement a ThreadLocal<T> class

问题 How is ThreadLocal implemented? Is it implemented in Java (using some concurrent map from ThreadID to object), or does it use some JVM hook to do it more efficiently? 回答1: All of the answers here are correct, but a little disappointing as they somewhat gloss over how clever ThreadLocal 's implementation is. I was just looking at the source code for ThreadLocal and was pleasantly impressed by how it's implemented. The Naive Implementation If I asked you to implement a ThreadLocal<T> class

问题 Does any one have an example how to do this? Are they handled by the garbage collector? I'm using Tomcat 6. 回答1: The javadoc says this: "Each thread holds an implicit reference to its copy of a thread-local variable as long as the thread is alive and the ThreadLocal instance is accessible; after a thread goes away, all of its copies of thread-local instances are subject to garbage collection (unless other references to these copies exist). If your application or (if you are talking about

问题 It is mentioned at multiple posts: improper use of ThreadLocal causes Memory Leak. I am struggling to understand how Memory Leak would happen using ThreadLocal . The only scenario I have figured out it as below: A web-server maintains a pool of Threads (e.g. for servlets). Those threads can create memory leak if the variables in ThreadLocal are not removed because Threads do not die. This scenario does not mention "Perm Space" memory leak. Is that the only (major) use case of memory leak? 回答1

问题 It is mentioned at multiple posts: improper use of ThreadLocal causes Memory Leak. I am struggling to understand how Memory Leak would happen using ThreadLocal . The only scenario I have figured out it as below: A web-server maintains a pool of Threads (e.g. for servlets). Those threads can create memory leak if the variables in ThreadLocal are not removed because Threads do not die. This scenario does not mention "Perm Space" memory leak. Is that the only (major) use case of memory leak? 回答1

问题 I am confused with the description of thread_local in C++11. My understanding is, each thread has unique copy of local variables in a function. The global/static variables can be accessed by all the threads (possibly synchronized access using locks). And the thread_local variables are visible to all the threads but can only modified by the thread for which they are defined? Is it correct? 回答1: Thread-local storage duration is a term used to refer to data that is seemingly global or static

问题 I am currently working on a RESTeasy based RESTful service. I have a filter class which serves as a server request filter as well as a server response filter (i.e. it implements ContainerRequestFilter and ContainerResponseFilter interfaces). At the beginning of the request, I use the filter to put an object into ThreadLocal . This object is used by the resources throughout the request. At the end of the request, before sending out the response, the filter removes the object from ThreadLocal .

问题 Running tests in parallel on a windows node and a mac node using selenium grid would pass all tests but fail to run and skip the first test FilterMoreResultsBySquareFeet for either the Mac Firefox browser or the Windows Firefox browser. It keeps throwing this error org.openqa.selenium.SessionNotCreatedException: Unable to create new service: GeckoDriverService I am using latest java, latest selenium driver, latest browser driver, and lastest browser version. I have all drivers in the same

问题 I have InheritableThreadLocal<ConcurrentHashMap<String, Object>> thread that initializes when a request comes via the filter and set some transaction_id in it. Now at the service layer, I'm calling 10 different API calls via CompletableFuture. All API service class have one execute method that is using RestTempate to make an API call. I put @HystrixCommand on execute method. execute method is void type but it put the API response in InheritableThreadLocal object. Problem is when an API call