(new submission) melgenek: ~top 15 on 10k. Buffered IO, VarHandles, vectors, custom hashtable (#600)

* melgenek: ~top 15 on 10k. Buffered IO, VarHandles, vectors, custom hashtable

* Calculate the required heap size dynamically

1 files changed, 37 insertions, 0 deletions

diff --git a/calculate_average_melgenek.sh b/calculate_average_melgenek.sh
new file mode 100755
index 0000000..e0a88a3
--- /dev/null
+++ b/calculate_average_melgenek.sh
@@ -0,0 +1,37 @@
+#!/bin/bash
+#
+#  Copyright 2023 The original authors
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+
+JAVA_OPTS="--enable-preview --add-modules jdk.incubator.vector -Djdk.incubator.vector.VECTOR_ACCESS_OOB_CHECK=0"
+JAVA_OPTS="$JAVA_OPTS -XX:+UnlockExperimentalVMOptions -XX:+UseEpsilonGC -XX:+AlwaysPreTouch"
+# These flags are mostly copied from the shipilev's branch. They don't really give a predictable benefit, but they don't hurt either.
+JAVA_OPTS="$JAVA_OPTS -XX:-TieredCompilation -XX:CICompilerCount=1 -XX:CompileThreshold=2048 -XX:-UseCountedLoopSafepoints -XX:+TrustFinalNonStaticFields"
+
+if [[ "$(uname -s)" == "Linux" ]]; then
+    JAVA_OPTS="$JAVA_OPTS -XX:+UseTransparentHugePages"
+fi
+
+# https://stackoverflow.com/a/23378780/7221823
+logicalCpuCount=$([ $(uname) = 'Darwin' ] &&
+                       sysctl -n hw.logicalcpu_max ||
+                       lscpu -p | egrep -v '^#' | wc -l)
+# The required heap is proportional to the number of cores.
+# There's roughly 3.5MB heap per thread required for the 10k problem.
+requiredMemory=$(echo "(l(15 + 3.5 * $logicalCpuCount)/l(2))" | bc -l)
+heapSize=$(echo "scale=0; 2^(($requiredMemory+1)/1)" | bc)
+
+JAVA_OPTS="$JAVA_OPTS -Xms${heapSize}m -Xmx${heapSize}m"
+java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_melgenek