Improve startup time by prelocating libjemalloc

This requires apache/cassandra-ccm#519 in order to work
correctly.

Author: thobbs

Diff for: dtest.py

@@ -115,6 +115,30 @@
     CASSANDRA_VERSION_FROM_BUILD = get_version_from_build(CASSANDRA_DIR)
 
 
+# Determine the location of the libjemalloc jar so that we can specify it
+# through environment variables when start Cassandra.  This reduces startup
+# time, making the dtests run faster.
+def find_libjemalloc():
+    if is_win():
+        # let the normal bat script handle finding libjemalloc
+        return ""
+
+    this_dir = os.path.dirname(os.path.realpath(__file__))
+    script = os.path.join(this_dir, "findlibjemalloc.sh")
+    try:
+        p = subprocess.Popen([script], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        stdout, stderr = p.communicate()
+        if stderr or not stdout:
+            return "-"  # tells C* not to look for libjemalloc
+        else:
+            return stdout
+    except Exception, exc:
+        print "Failed to run script to prelocate libjemalloc ({}): {}".format(script, exc)
+        return ""
+
+CASSANDRA_LIBJEMALLOC = find_libjemalloc()
+
+
 class expect_control_connection_failures(object):
     """
     We're just using a class here as a one-off object with a filter method, for
@@ -270,6 +294,7 @@ def _get_cluster(self, name='test'):
             cluster.set_configuration_options(values={'memtable_allocation_type': 'offheap_objects'})
 
         cluster.set_datadir_count(DATADIR_COUNT)
+        cluster.set_environment_variable('CASSANDRA_LIBJEMALLOC', CASSANDRA_LIBJEMALLOC)
 
         return cluster
 

Diff for: findlibjemalloc.sh

@@ -0,0 +1,35 @@
+#!/bin/sh
+
+# taken from bin/cassandra
+
+find_library()
+{
+    pattern=$1
+    path=$(echo ${2} | tr ":" " ")
+    find $path -regex "$pattern" -print 2>/dev/null | head -n 1
+}
+
+case "`uname -s`" in
+    Linux)
+        which ldconfig > /dev/null 2>&1
+        if [ $? = 0 ] ; then
+            # e.g. for CentOS
+            dirs="/lib64 /lib /usr/lib64 /usr/lib `ldconfig -v 2>/dev/null | grep -v '^\s' | sed 's/^\([^:]*\):.*$/\1/'`"
+        else
+            # e.g. for Debian, OpenSUSE
+            dirs="/lib64 /lib /usr/lib64 /usr/lib `cat /etc/ld.so.conf /etc/ld.so.conf.d/*.conf | grep '^/'`"
+        fi
+        dirs=`echo $dirs | tr " " ":"`
+        CASSANDRA_LIBJEMALLOC=$(find_library '.*/libjemalloc\.so\(\.1\)*' $dirs)
+    ;;
+    Darwin)
+        CASSANDRA_LIBJEMALLOC=$(find_library '.*/libjemalloc\.dylib' $DYLD_LIBRARY_PATH:${DYLD_FALLBACK_LIBRARY_PATH-$HOME/lib:/usr/local/lib:/lib:/usr/lib})
+    ;;
+esac
+
+if [ ! -z $CASSANDRA_LIBJEMALLOC ] ; then
+    echo $(CASSANDRA_LIBJEMALLOC)
+    exit 0
+else
+    exit 1
+fi