- 2014-05-23 01:41:40.056 customtype44170:1b03 +NSUndoManager(NSInternal) endTopLevelGroupings is only safe to invoke on the main thread. This is a message coming from Mac OS itself, and it's my understanding that the event loop is in fact running by then.
- The debugger supports thread debugging, signal handling, non-interactive tracing, and much more. This was written in the era of Python 2.4-2.6. See trepan3k below. Xpdb: Unix: pdb extension with curses module that adds console window with source code. JpyDbg: Mac OS X, OS/2, Unix, VMS and Windows.
There is a way of thread execution inside the process of any operating system. Apart from this, there can be more than one thread inside a process. Thread is often referred to as a lightweight process.
The process can be split down into so many threads. For example, in a browser, many tabs can be viewed as threads. MS Word uses many threads - formatting text from one thread, processing input from another thread, etc.
Types of Threads
From the Apple menu in the corner of your screen, choose About This Mac. You should see the macOS name, such as macOS Big Sur, followed by its version number. If you need to know the build number as well, click the version number to see it. Which macOS version is the latest? I have an issue causing an app crash when the background thread (in a shelled process) has been ignored for too long and Mac OS setting its Zombie flag so that I can’t wake it up again. From one of the crash reports: Effective Thread QoS Default, Requested Thread QoS Default, Override Thread QoS Unspecified. I’m clutching at straws here.
In the operating system, there are two types of threads.
- Kernel level thread.
- User-level thread.
User-level thread
The operating system does not recognize the user-level thread. User threads can be easily implemented and it is implemented by the user. If a user performs a user-level thread blocking operation, the whole process is blocked. The kernel level thread does not know nothing about the user level thread. The kernel-level thread manages user-level threads as if they are single-threaded processes?examples: Java thread, POSIX threads, etc.
Advantages of User-level threads
- The user threads can be easily implemented than the kernel thread.
- User-level threads can be applied to such types of operating systems that do not support threads at the kernel-level.
- It is faster and efficient.
- Context switch time is shorter than the kernel-level threads.
- It does not require modifications of the operating system.
- User-level threads representation is very simple. The register, PC, stack, and mini thread control blocks are stored in the address space of the user-level process.
- It is simple to create, switch, and synchronize threads without the intervention of the process.
Disadvantages of User-level threads
- User-level threads lack coordination between the thread and the kernel.
- If a thread causes a page fault, the entire process is blocked.
Kernel level thread
Threaded Mac Os Download
The kernel thread recognizes the operating system. There are a thread control block and process control block in the system for each thread and process in the kernel-level thread. The kernel-level thread is implemented by the operating system. The kernel knows about all the threads and manages them. The kernel-level thread offers a system call to create and manage the threads from user-space. The implementation of kernel threads is difficult than the user thread. Context switch time is longer in the kernel thread. If a kernel thread performs a blocking operation, the Banky thread execution can continue. Example: Window Solaris.
Advantages of Kernel-level threads
- The kernel-level thread is fully aware of all threads.
- The scheduler may decide to spend more CPU time in the process of threads being large numerical.
- The kernel-level thread is good for those applications that block the frequency.
Disadvantages of Kernel-level threads
- The kernel thread manages and schedules all threads.
- The implementation of kernel threads is difficult than the user thread.
- The kernel-level thread is slower than user-level threads.
Components of Threads
Any thread has the following components.
- Program counter
- Register set
- Stack space
Benefits of Threads
- Enhanced throughput of the system: When the process is split into many threads, and each thread is treated as a job, the number of jobs done in the unit time increases. That is why the throughput of the system also increases.
- Effective Utilization of Multiprocessor system: When you have more than one thread in one process, you can schedule more than one thread in more than one processor.
- Faster context switch: The context switching period between threads is less than the process context switching. The process context switch means more overhead for the CPU.
- Responsiveness: When the process is split into several threads, and when a thread completes its execution, that process can be responded to as soon as possible.
- Communication: Multiple-thread communication is simple because the threads share the same address space, while in process, we adopt just a few exclusive communication strategies for communication between two processes.
- Resource sharing: Resources can be shared between all threads within a process, such as code, data, and files. Note: The stack and register cannot be shared between threads. There are a stack and register for each thread.