T-Z

thread An independent flow of control within a single process, having its

 

own register set and program counter. The HP-UX operating system supports

 

multiple-executing threads within the same process.

Thread Trace

See ttv

Visualizer

 

trap

A change in system state that is caused by an exception and that may be

 

detected by the executing program that took the exception. Traps are

 

hardware features that may be enabled or disabled. If traps are enabled,

 

they can change the flow of control in the program that took the exception.

 

In response to a trap, the system may generate a signal (for example,

 

SIGFPE), which the program can detect. Such a program can be designed

 

to handle traps. HP Fortran 90 provides the ONstatement to handle traps.

ttv

A tool for analyzing parallel-executing programs.

tty buffering

A method for efficiently processing data that is directed to standard output

 

by capturing it in a buffer before sending it to the screen.

underflow An

condition that occurs when the result of a floating-point operation is smaller

exception

than the smallest normalized number. On systems that support it, fast

 

underflow is an efficient method of handling this exception.

vectorization

An optimization technique that replaces eligible program loops that operate

 

on arrays with calls to specially tuned routines that perform the same

 

operation.

wall-clock time

Time spent by an executing program that includes system time as well as

 

process time. In contrast, virtual time takes into account process time only.

 

Profilers (such as CXperf) that track both virtual time and wall-clock time

 

provide information about when a program is blocked as well as when it

 

is running.

HP WDB

The HP Wildebeest Debugger (WDB) is an HP-supported implementation

 

of the Open Source GNU debugger (GDB).

158 Glossary