Improve benchmarks and tests for threads.

benchmark/vm_thread_alive_check.yml

@@ -0,0 +1,8 @@
+benchmark:
+  vm_thread_alive_check: |
+    t = Thread.new{}
+    while t.alive?
+      Thread.pass
+    end
+loop_count: 50_000
+

benchmark/vm_thread_alive_check1.rb

@@ -1,6 +0,0 @@
-5_000.times{
-  t = Thread.new{}
-  while t.alive?
-    Thread.pass
-  end
-}

benchmark/vm_thread_pass.rb

@@ -1,8 +1,8 @@
 # Plenty Thtread.pass
 # A performance may depend on GVL implementation.
 
-tmax = (ARGV.shift || 2).to_i
-lmax = 200_000 / tmax
+tmax = (ARGV.shift || 8).to_i
+lmax = 400_000 / tmax
 
 (1..tmax).map{
   Thread.new{

benchmark/vm_thread_pass_flood.rb

@@ -1,10 +1,10 @@
 # n.b. this is a good test for GVL when pinned to a single CPU
 
-1000.times{
+5_000.times{
   Thread.new{loop{Thread.pass}}
 }
 
 i = 0
-while i<10000
+while i<10_000
   i += 1
 end

benchmark/vm_thread_queue.rb

@@ -1,6 +1,6 @@
 require 'thread'
 
-n = 1_000_000
+n = 10_000_000
 q = Thread::Queue.new
 consumer = Thread.new{
   while q.pop

benchmark/vm_thread_sleep.yml

@@ -0,0 +1,4 @@
+benchmark:
+  vm_thread_sleep: |
+    Thread.new { sleep }
+loop_count: 10_000

bootstraptest/test_thread.rb

@@ -10,6 +10,9 @@ assert_equal %q{ok}, %q{
     :ok
   }.value
 }
+assert_equal %q{ok}, %q{
+  :ok if Thread.new{sleep}.backtrace == []
+}
 assert_equal %q{ok}, %q{
 begin
   v = 0