improve ULT stack size configuration

[shintaro-iwasaki]

Pull Request Description

ULT stack overflow causes numerous issues (see #274, #324, #333, and this thread). This PR adds new features to ease stack size configuration.

1. Configure-time stack size setting

The user can configure a default ULT stack size.

./configure --enable-default-stacksize=102400

This setting can be overwritten by ABT_THREAD_STACKSIZE

# The default ULT stack size is that of configure-time (e.g., 102400)
./a.out
# The default ULT stack size is 204800 
ABT_THREAD_STACKSIZE=204800 ./a.out

2. Run-time stack size check

If --enable-ver20-api is set, the application can now obtain the default stack size via ABT_info_query_config() without initializing Argobots (i.e., before ABT_init()).

// Argobots configured with --enable-ver20-api
size_t stacksize;
ABT_info_query_config(ABT_INFO_QUERY_KIND_DEFAULT_THREAD_STACKSIZE, (void *)&stacksize);
assert(stacksize >= 65536);

Note that by default (without --enable-ver20-api), ABT_info_query_config() needs Argobots initialization to maintain the backward compatibility of API.

// Default Argobots configuration
ABT_init(0, 0);
size_t stacksize;
// If ABT_info_query_config() is called without initializing Argobots, an error is returned.
ABT_info_query_config(ABT_INFO_QUERY_KIND_DEFAULT_THREAD_STACKSIZE, (void *)&stacksize);
assert(stacksize >= 65536);
ABT_finalize();

This PR does not change the default ULT stack size (16KB).

Checklist

• Reference appropriate issues (with "Fixes" or "See" as appropriate)
• Commits are self-contained and do not do two things at once
• Commit message is of the form: module: short description and follows good practice
• Passes whitespace checkers

[shintaro-iwasaki]

test:argobots/all

[shintaro-iwasaki]

test:argobots/all