Use block form of IO.popen to prevent zombies

Author: matthewd

lib/concurrent/utility/processor_counter.rb

@@ -86,27 +86,25 @@ def compute_processor_count
               "select NumberOfLogicalProcessors from Win32_Processor")
             result.to_enum.collect(&:NumberOfLogicalProcessors).reduce(:+)
           elsif File.executable?("/usr/bin/nproc")
-            IO.popen("/usr/bin/nproc --all").read.to_i
+            IO.popen("/usr/bin/nproc --all", &:read).to_i
           elsif File.readable?("/proc/cpuinfo")
             IO.read("/proc/cpuinfo").scan(/^processor/).size
           elsif File.executable?("/usr/bin/hwprefs")
-            IO.popen("/usr/bin/hwprefs thread_count").read.to_i
+            IO.popen("/usr/bin/hwprefs thread_count", &:read).to_i
           elsif File.executable?("/usr/sbin/psrinfo")
-            IO.popen("/usr/sbin/psrinfo").read.scan(/^.*on-*line/).size
+            IO.popen("/usr/sbin/psrinfo", &:read).scan(/^.*on-*line/).size
           elsif File.executable?("/usr/sbin/ioscan")
-            IO.popen("/usr/sbin/ioscan -kC processor") do |out|
-              out.read.scan(/^.*processor/).size
-            end
+            IO.popen("/usr/sbin/ioscan -kC processor", &:read).scan(/^.*processor/).size
           elsif File.executable?("/usr/sbin/pmcycles")
-            IO.popen("/usr/sbin/pmcycles -m").read.count("\n")
+            IO.popen("/usr/sbin/pmcycles -m", &:read).count("\n")
           elsif File.executable?("/usr/sbin/lsdev")
-            IO.popen("/usr/sbin/lsdev -Cc processor -S 1").read.count("\n")
+            IO.popen("/usr/sbin/lsdev -Cc processor -S 1", &:read).count("\n")
           elsif File.executable?("/usr/sbin/sysconf") and os_name =~ /irix/i
-            IO.popen("/usr/sbin/sysconf NPROC_ONLN").read.to_i
+            IO.popen("/usr/sbin/sysconf NPROC_ONLN", &:read).to_i
           elsif File.executable?("/usr/sbin/sysctl")
-            IO.popen("/usr/sbin/sysctl -n hw.ncpu").read.to_i
+            IO.popen("/usr/sbin/sysctl -n hw.ncpu", &:read).to_i
           elsif File.executable?("/sbin/sysctl")
-            IO.popen("/sbin/sysctl -n hw.ncpu").read.to_i
+            IO.popen("/sbin/sysctl -n hw.ncpu", &:read).to_i
           else
             1
           end
@@ -118,7 +116,7 @@ def compute_processor_count
       def compute_physical_processor_count
         ppc = case RbConfig::CONFIG["target_os"]
               when /darwin1/
-                IO.popen("/usr/sbin/sysctl -n hw.physicalcpu").read.to_i
+                IO.popen("/usr/sbin/sysctl -n hw.physicalcpu", &:read).to_i
               when /linux/
                 cores = {} # unique physical ID / core ID combinations
                 phy   = 0