Python Reference

Managed Objects

Unlike threads, processes do not support shared objects. Although you can create shared values and arrays as shown in the previous section, this doesn't work for more advanced Python objects such as dictionaries, lists, or instances of user-defined classes.The multiprocessing module does, however, provide a way to work with shared objects if they run under the control of a so-called manager.A manager is a separate subprocess where the real objects exist and which operates as a server. Other...

Semaphore and Bounded Semaphore

A semaphore is a synchronization primitive based on a counter that's decremented by each acquire call and incremented by each release call. If the counter ever reaches zero, the acquire method blocks until some other thread calls release . Creates a new semaphore. value is the initial value for the counter. If omitted, the counter is set to a value of 1. A Semaphore instance, s, supports the following methods Acquires the semaphore. If the internal counter is larger than zero on entry, this...

Type Conversion from C to Python

The following C function is used to convert the values contained in C variables to a Python object PyObject Py_BuildValue char format, This constructs a Python object from a series of C variables. format is a string describing the desired conversion. The remaining arguments are the values of C variables to be converted. The format specifier is similar to that used with the PyArg_ParseTuple functions, as shown in Table 26.4. Table 26.4 Format Specifiers for Py_BuiidVaiue s String char s String...