Eric Lippert has a nice blog post entitled What is this thing you call “thread safe”? about the definition of thread safety as found of Wikipedia. 3 important things extracted from the links : “A piece of code is thread-safe if it functions correctly during simultaneous execution by multiple threads.” “In particular, it must satisfy the need for … Read more
JavaScript does not support multi-threading because the JavaScript interpreter in the browser is a single thread (AFAIK). Even Google Chrome will not let a single web page’s JavaScript run concurrently because this would cause massive concurrency issues in existing web pages. All Chrome does is separate multiple components (different tabs, plug-ins, etcetera) into separate processes, … Read more
You keep updating both high and low inside the run() method, making them by definition not effectively final. Since you don’t need them outside the run() method anyway, just move the two lines inside.
One solution to this problem is to use the Handler.postDelayed() method. Some Google training materials suggest the same solution. However, some have pointed out that the solution above causes a memory leak because it uses a non-static inner and anonymous class which implicitly holds a reference to its outer class, the activity. This is a … Read more
Cross-thread signals are thread-safe, so calling the updatePB method in your example is okay. Your ConnDisconn method is not thread-safe, but that has got nothing to do with PyQt or Qt – it’s just a consequence of how you wrote it. The serialEnabled attribute could be read/written by two threads simultaneously, so the behaviour is strictly undefined. A thread-safe way of … Read more
PyQt is thread-safe to the same extent that Qt is thread-safe. The Qt docs will tell you which parts of their API are guaranteed to be so, and under what circumstances. Cross-thread signals are thread-safe, so calling the updatePB method in your example is okay. Your ConnDisconn method is not thread-safe, but that has got nothing to do with … Read more
PyQt is thread-safe to the same extent that Qt is thread-safe. The Qt docs will tell you which parts of their API are guaranteed to be so, and under what circumstances. Cross-thread signals are thread-safe, so calling the updatePB method in your example is okay. Your ConnDisconn method is not thread-safe, but that has got … Read more
I don’t know why you’re using the Window’s Mutex instead of Python’s. Using the Python methods, this is pretty simple: But note, because of the architecture of CPython (namely the Global Interpreter Lock) you’ll effectively only have one thread running at a time anyway–this is fine if a number of them are I/O bound, although … Read more
You have to move the portion of the background task that updates the UI onto the main thread. There is a simple piece of code for this: Documentation for Activity.runOnUiThread. Just nest this inside the method that is running in the background, and then copy paste the code that implements any updates in the middle … Read more
It is generally a bad pattern to kill a thread abruptly, in Python, and in any language. Think of the following cases: the thread is holding a critical resource that must be closed properly the thread has created several other threads that must be killed as well. The nice way of handling this, if you … Read more