Re: Where static local variable allocate?

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Fri, 23 May 2008 01:42:19 -0700 (PDT)
Message-ID:
<82edf274-b4f5-4090-87ea-b33b2257e42a@79g2000hsk.googlegroups.com>
On May 23, 8:58 am, "Neil.Fang.CN" <NeilFang2...@gmail.com> wrote:

Supposing I have a class like this:

class SomeManager
{
public:
  static SomeManager& getInstance();
}

SomeManager& SomeManager::getInstance()
{
  static SomeManager instance;
  return instance;
}

Will the ? static SomeManager instance;? allocated in
stack? If so, this will failed in multi-threads, because every
thread have it's own stack?


No.

Technically, the issue isn't where the variable is allocated,
but its lifetime; the lifetime of a local static starts the
first time the execution path reaches it, and ends sometimes
after exit() has been called (which may cause problems in a
multithreaded environment, depending on how you manage
shutdown). This is called "static lifetime", and in practice,
means that the variable won't be allocated on the runtime stack.
(There is a stack of sorts involved, since the order of
destruction of such objects must be the reverse of the order of
construction.)

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James Kanze (GABI Software) email:james.kanze@gmail.com
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