concurrency

问题 I'm trying to write a thread-safe queue using pthreads in c++. My program works 93% of the time. The other 7% of the time it other spits out garbage, OR seems to fall asleep. I'm wondering if there is some flaw in my queue where a context-switch would break it? // thread-safe queue // inspired by http://msmvps.com/blogs/vandooren/archive/2007/01/05/creating-a-thread-safe-producer-consumer-queue-in-c-without-using-locks.aspx // only works with one producer and one consumer #include <pthread.h>

问题 I'm trying to create an AWS SQS windows service consumer that will poll messages in batch of 10. Each messages will be executed in its own task for parallel execution. Message processing includes calling different api's and sending email so it might take some time. My problem is that first, I only want to poll the queue when 10 messages can be processed immediately. This is due to sqs visibility timeout and having the received messages "wait" might go over the visibility timeout and be "back"

问题 Here the code class Aux implements Runnable { private Boolean isOn = false; private String statusMessage; private final Object lock; public Aux(String message, Object lock) { this.lock = lock; this.statusMessage = message; } @Override public void run() { for (;;) { synchronized (lock) { if (isOn && "left".equals(this.statusMessage)) { isOn = false; System.out.println(statusMessage); } else if (!isOn && "right".equals(this.statusMessage)) { isOn = true; System.out.println(statusMessage); } if

问题 Here the code class Aux implements Runnable { private Boolean isOn = false; private String statusMessage; private final Object lock; public Aux(String message, Object lock) { this.lock = lock; this.statusMessage = message; } @Override public void run() { for (;;) { synchronized (lock) { if (isOn && "left".equals(this.statusMessage)) { isOn = false; System.out.println(statusMessage); } else if (!isOn && "right".equals(this.statusMessage)) { isOn = true; System.out.println(statusMessage); } if

问题 I'm working on ThreadPoolExcutor . I would like to know if in invokeAll method, I can be sure that the output ( Future objects) order is going to be the same as the input ( Callable list). List<Future<T>> invokeAll(List<Callable<T>> tasks) 回答1: What is guaranteed is that the list of futures returned has the same order that the list's iterator you're giving. Note that this method only returns when all tasks have been completed. Quoting invokeAll(tasks) Javadoc: Returns: a list of Futures

问题 I'm working on ThreadPoolExcutor . I would like to know if in invokeAll method, I can be sure that the output ( Future objects) order is going to be the same as the input ( Callable list). List<Future<T>> invokeAll(List<Callable<T>> tasks) 回答1: What is guaranteed is that the list of futures returned has the same order that the list's iterator you're giving. Note that this method only returns when all tasks have been completed. Quoting invokeAll(tasks) Javadoc: Returns: a list of Futures

问题 I'm using Polly to make parallel API calls. The server however can't process more than 25 calls per second and so I'm wondering if there is a way to add a 1s delay after each batch of 25 calls? var policy = Policy .Handle<HttpRequestException>() .RetryAsync(3); foreach (var mediaItem in uploadedMedia) { var mediaRequest = new HttpRequestMessage { *** } async Task<string> func() { var response = await client.SendAsync(mediaRequest); return await response.Content.ReadAsStringAsync(); } tasks

问题 I'm using Polly to make parallel API calls. The server however can't process more than 25 calls per second and so I'm wondering if there is a way to add a 1s delay after each batch of 25 calls? var policy = Policy .Handle<HttpRequestException>() .RetryAsync(3); foreach (var mediaItem in uploadedMedia) { var mediaRequest = new HttpRequestMessage { *** } async Task<string> func() { var response = await client.SendAsync(mediaRequest); return await response.Content.ReadAsStringAsync(); } tasks

问题 I have a process that grows a NetCDF file fn every 5 minutes using netcdf4.Dataset(fn, mode=a) . I also have a bokeh server visualization of that NetCDF file using a xarray.Dataset (which I want to keep, because it is so convenient). The problem is that the NetCDF-update-process fails when trying to add new data to fn if it is open in my bokeh server process via ds = xarray.open_dataset(fn) If I use the option autoclose ds = xarray.open_dataset(fn, autoclose=True) updating fn with the other

问题 I'm using Polly to make parallel API calls. The server however can't process more than 25 calls per second and so I'm wondering if there is a way to add a 1s delay after each batch of 25 calls? var policy = Policy .Handle<HttpRequestException>() .RetryAsync(3); foreach (var mediaItem in uploadedMedia) { var mediaRequest = new HttpRequestMessage { *** } async Task<string> func() { var response = await client.SendAsync(mediaRequest); return await response.Content.ReadAsStringAsync(); } tasks