BeginThread

Initiates a new thread of execution within the current thread group

Local Servers:blocking
Remote Servers:N/A
Classification:3.x, 4.x, 5.x, 6.x
Service:Thread

Syntax

  #include <nwthread.h>  
   
  int BeginThread  (  
     void       (*func) (void *),  
     void       *stack,   
     unsigned    stackSize,   
     void       *arg);

Parameters

func
(IN) Points to the function to execute as the new thread.
stack
(IN) Points to a block of memory to use for the new thread’s stack.
stackSize
(IN) Specifies the size (in bytes) of the stack.
arg
(IN) Points to an argument to be passed to the new thread.

Return Values

This function returns the new thread’s ID if successful. It returns EFAILURE if an error occurs.

If an error occurs, errno is set to:

Value

Name

Description

5

ENOMEM

Not enough memory.

9

EINVAL

Invalid argument was passed in.

Remarks

The new thread begins execution at the specified function ( func). The function func receives arg as a parameter. The stack parameter is a pointer to a block of memory that the new thread uses as its stack.

  • If stack is NULL, a block of memory (as specified by the stackSize parameter) is allocated.
  • If stack is NULL and the specified stack size is too small, the size for the new thread stack is increased automatically.
  • If stack is not NULL and the specified stack size is too small, the function fails and errno is set to EINVAL. The minimum stack size for the 3.x OS is 2,064 bytes and 16,384 bytes for the NetWare 4.x, 5.x, and 6.x OS.
  • If stackSize is zero and stack is NULL, then the default stack size (8,192 bytes for 3.x or 16,384 bytes for 4.x, 5.x, and 6.x) is used.

The arg parameter is any 32-bit quantity, although typically some sort of pointer is passed, or NULL is passed if the specified function does not take any arguments.

If the newly created thread returns from the function func, it is be equivalent to its having executed the ExitThread function with an action code of EXIT_THREAD.

To begin a thread in a new thread group, call BeginThreadGroup.

See Also

BeginThreadGroup, ExitThread

Example

  #include <nwthread.h>  
   
  void newThreadFunc (char *funcArg);  
  int      completionCode;  
  .  
  .  
  .  
  completionCode = BeginThread (newThreadFunc, NULL, 8192, /A/Q
       "input.fil");  
  .  
  .  
  .  
  void newThreadFunc (char *arg)  
  {  
     printf ("in new thread\n");  
  }