Re: stack overflow?
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- Subject: Re: stack overflow?
- From: Rici Lake <lua@...>
- Date: 2005年8月30日 16:56:07 -0500
On 30-Aug-05, at 4:24 PM, Brent Arias wrote:
How big can the lua stack get, before it overflows?
Assuming you have enough memory, the limitations are the values in
src/llimits.h (5.0.2) or src/luaconf.h (5.1)
LUA_MAXCALLS determines the maximum number of call frames. In 5.0.2 it
was a short, but it seems that in 5.1 it's an int, so you could set it
a lot higher if you wanted to.
LUA_MAXCCALLS is the maximum number of recursive entries to the VM
itself; in effect, the maximum number of C (as opposed to Lua) call
frames. It's much smaller. I think that 10 would suffice for 99.9% of
Lua programs, but the default value is a bit more than that.
The maximum size of a C stack frame is controlled by LUA_MAXCSTACK, by
default 2048. C programs need to use lua_checkstack() if they are
planning on using more than LUA_MINSTACK slots (that one is defined in
lua.h)
By the way, the largest possible Lua stack frame is 255 slots.
(LUA_MAXSTACK + LUA_EXTRA_STACK, but don't change these!) The actual
size of a stack frame used by a Lua function is set at compile time to
the actual number of slots needed; this rarely exceeds 20 and is often
much smaller, like 4.
If you're asking because you want to have very deep recursion, you
should increase LUA_MAXCALLS, remembering that in 5.0.2 it's a short.
If you're asking because you want to protect yourself from deep
recursion, then you might want to decrease it.
Also, is there a
hard-limit restriction of how many coroutines can be created/used? Is
there
a limit or restriction on how many coroutines may be simultaneously
yielded?
It would basically be a memory limit.