deadlock

问题 I'm writing a program which needs to recursively search through a folder structure, and would like to do so in parallel with several threads. I've written the rather trivial synchronous method already - adding the root directory to the queue initially, then dequeuing a directory, queuing its subdirectories, etc., until the queue is empty. I'll use a ConcurrentQueue<T> for my queue, but have already realized that my loops will stop prematurely. The first thread will dequeue the root directory,

问题 I'm writing a program which needs to recursively search through a folder structure, and would like to do so in parallel with several threads. I've written the rather trivial synchronous method already - adding the root directory to the queue initially, then dequeuing a directory, queuing its subdirectories, etc., until the queue is empty. I'll use a ConcurrentQueue<T> for my queue, but have already realized that my loops will stop prematurely. The first thread will dequeue the root directory,

问题 I'm writing a program which needs to recursively search through a folder structure, and would like to do so in parallel with several threads. I've written the rather trivial synchronous method already - adding the root directory to the queue initially, then dequeuing a directory, queuing its subdirectories, etc., until the queue is empty. I'll use a ConcurrentQueue<T> for my queue, but have already realized that my loops will stop prematurely. The first thread will dequeue the root directory,

问题 I am studying java threads and deadlocks, I understand deadlock's examples but I wonder if there are general rules to follow to prevent it. My question is if there are rules or tips that can be applied to the source code in java to prevent deadlocks? If yes, could you explain how to implement it? 回答1: Some quick tips out of my head don't use multiple threads (like Swing does, for example, by mandating that everything is done in the EDT) don't hold several locks at once. If you do, always

问题 >>> import concurrent.futures >>> from collections import namedtuple >>> #1. Initialise namedtuple here >>> # tm = namedtuple("tm", ["pk"]) >>> class T: ... #2. Initialise named tuple here ... #tm = namedtuple("tm", ["pk"]) ... def __init__(self): ... #3: Initialise named tuple here ... tm = namedtuple("tm", ["pk"]) ... self.x = {'key': [tm('value')]} ... def test1(self): ... with concurrent.futures.ProcessPoolExecutor(max_workers=1) as executor: ... results = executor.map(self.test, ["key"])

问题 As best as I can, I opt for async all the way down. However, I am still stuck using ASP.NET Membership which isn't built for async. As a result my calls to methods like string[] GetRolesForUser() can't use async. In order to build roles properly I depend on data from various sources so I am using multiple tasks to fetch the data in parallel: public override string[] GetRolesForUser(string username) { ... Task.WaitAll(taskAccounts, taskContracts, taskOtherContracts, taskMoreContracts,

问题 when i press test my application with spring boot 2.1.9.RELEASE and tomcat 9.0.26 i meet a deadlock. It's maybe a bug with tomcat. when i use tomcat 8.5.49 instead the bug is not appear. The follow is the stack i dump from my application. Found one Java-level deadlock: ============================= "http-nio-8080-exec-455": waiting to lock monitor 0x00007f59c40475e8 (object 0x00000006c0b4fe28, a java.util.HashSet), which is held by "http-nio-8080-ClientPoller" "http-nio-8080-ClientPoller":

问题 I am in a situation where my program is deadlocking and I want to debug this and tell how many elements are in an unbuffered channel, is there any way to do this in Go? The following code does not output a 2 as I would expect (further it deadlocks, which is also something I cannot find a reason for) package main import "fmt" func main() { channel := make(chan string) done_channel := make(chan bool) go func() { channel <- "value" channel <- "value" fmt.Println(len(channel)) done_channel <-

问题 1.I have a script, that executes some update/delete operations 2.All sql operations are executed inside transaction(InnoDb tables) 3.From time to time I get "Deadlock found when trying to get lock; try restarting transaction" There are some other jobs in this application, that perform database operations. My problem is to find which concurrent queries from other scripts interfere my script. What is the easiest way to find them? 回答1: Haven't tried it but How to find out who is locking a table

问题 1.I have a script, that executes some update/delete operations 2.All sql operations are executed inside transaction(InnoDb tables) 3.From time to time I get "Deadlock found when trying to get lock; try restarting transaction" There are some other jobs in this application, that perform database operations. My problem is to find which concurrent queries from other scripts interfere my script. What is the easiest way to find them? 回答1: Haven't tried it but How to find out who is locking a table