© Thomas Kunz 2000
SCE 574
201
Stacks in a Concurrent Program
äWhat does the stack
look like in a concurrent program?
äNo longer a single
stack
äEach thread needs
its own stack
äStack space can be
allocated from a heap
äIssue becomes
complex in a language like Ada with sophisticated
scoping rules
Task A specification and body
Local variable a
Task B specification and body
Task C specification and body
Procedure D
End Task A
äLocal variables are
placed on the stack, how are they linked
together?
äA complex
multi-linked list data structure called a cactus
stack!
äWhat would the
assembler sequences look like for accessing a local variable in main from C?
D
A
B
C
Main
Body of A has
called procedure D
These are
two separate
stacks for
tasks B and C
They can
still access D and a
via A’s
stack, and main’s
variables as
well
More
tasks
from main,
each
task gets its
own
stack
