multithreading

问题 I'm programming with Tasks and await/async. I assumed that the multithreading works like it does in NodeJS or Python, that is, it doesn't, everything just runs on the same thread. But I've been trying to learn how Tasks actually get executed and my understanding is that they're executed by TaskScheduler.Default who's implementation is hidden but can be expected to use a ThreadPool. Should I be programming as if all my Tasks can run in any thread? The extent of my asynchronous programming is

问题 I'm writing a Google Sheets add-on that copies some data from one spreadsheet to another and then reformats it. The data sets involved are often large (~100k rows), so to avoid hitting the 6-minute timeout limit I break the data into chunks and then run the data-copying function in parallel on each chunk using google.script.run calls from the client side. On my sample data set of ~100k rows, the first couple of chunks to complete are copied successfully, and the rest are throwing the error

问题 In my application I have multithreads that needs to access database and I am using apache.tomcat.jdbc.pool.DataSource as a JDBC connection pool. In some cases users execute stored procedures that might affect the database session context/variables before executing another query to retrieve some data. After a thread is finished, connection is closed but the way the pooled connections work, the connection is not actually closed but rather returned to the connection pool for reuse. The problem

问题 In my application I have multithreads that needs to access database and I am using apache.tomcat.jdbc.pool.DataSource as a JDBC connection pool. In some cases users execute stored procedures that might affect the database session context/variables before executing another query to retrieve some data. After a thread is finished, connection is closed but the way the pooled connections work, the connection is not actually closed but rather returned to the connection pool for reuse. The problem

问题 Goal I have a process that logs on a file (realtime.log) while running and I want to print every new line of that file in my application in realtime. In other words I want to redirect the output from the process to the GUI. This means that I have two different processes running: the "engine" and the GUI. I have already achieved this by using Tkinter but since I have to make a more complex, professional and good looking GUI I decided to switch to Qt for Python ( PySide2 ). Problem Python often

问题 I need to increment global variable from several callbacks (event handlers), which may fire simultaneously. Do I need to worry about simultaneous access to that variable? Is there any analog of Interlocked.Increment like in C#? 回答1: Is there any analog of Interlocked.Increment in JavaScript? Yes, but you don't need it for your scenario.¹ I mean I need to increment global value from several different callbacks (event handlers), which may fire simultaneously. They will never fire simultaneously

问题 I have 1 method that I want to run in 10 different parallel threads, all will be independent there are no dependency on each other, my problem is that if I have 100 items to process and would like to process 10 at a time then how do in run 10 at a time. I have created a sample code where I am using Parallel.ForEach but what do I need to set so it should run 10 threads at a time and suppose any of the the running task have completed then it should automatically take new one, so all 10 threads

问题 I have 1 method that I want to run in 10 different parallel threads, all will be independent there are no dependency on each other, my problem is that if I have 100 items to process and would like to process 10 at a time then how do in run 10 at a time. I have created a sample code where I am using Parallel.ForEach but what do I need to set so it should run 10 threads at a time and suppose any of the the running task have completed then it should automatically take new one, so all 10 threads

问题 I have a large file almost 20GB , more than 20 mln lines and each line represents separate serialized JSON . Reading file line by line as a regular loop and performing manipulation on line data takes a lot of time . Is there any state of art approach or best practices for reading large files in parallel with smaller chunks in order to make processing faster? I'm using Python 3.6.X 回答1: Unfortunately, no. Reading in files and operating on the lines read (such as json parsing or computation) is

问题 In what situation would anyone ever use the no-argument constructor of the Java Thread class? The API says: This constructor has the same effect as Thread(null, null, gname), where gname is a newly generated name. Correct me if I am wrong, but I think the target of the thread can not be modified after the new Thread object is instantiated. If the target equals null then the start method will do nothing right? Why would you use this constructor? 回答1: For one thing, it allows you to create