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Added comments to used flags, clean up code, final fine tuning. (#674)
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@thomaswue
thomaswue authored Jan 31, 2024
1 parent 7f0e517 commit a5ce4ba
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16 changes: 14 additions & 2 deletions prepare_thomaswue.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,19 @@ sdk use java 21.0.2-graal 1>&2

# ./mvnw clean verify removes target/ and will re-trigger native image creation.
if [ ! -f target/CalculateAverage_thomaswue_image ]; then
NATIVE_IMAGE_OPTS="--gc=epsilon -O3 -H:TuneInlinerExploration=1 -march=native --enable-preview --initialize-at-build-time=dev.morling.onebrc.CalculateAverage_thomaswue\$Scanner"
# Use -H:MethodFilter=CalculateAverage_thomaswue.* -H:Dump=:2 -H:PrintGraph=Network for IdealGraphVisualizer graph dumping.

# Performance tuning flags, optimization level 3, maximum inlining exploration, and compile for the architecture where the native image is generated.
NATIVE_IMAGE_OPTS="-O3 -H:TuneInlinerExploration=1 -march=native"

# Need to enable preview for accessing the raw address of the foreign memory access API.
# Initializing the Scanner to make sure the unsafe access object is known as a non-null compile time constant.
NATIVE_IMAGE_OPTS="$NATIVE_IMAGE_OPTS --enable-preview --initialize-at-build-time=dev.morling.onebrc.CalculateAverage_thomaswue\$Scanner"

# There is no need for garbage collection and therefore also no safepoints required.
NATIVE_IMAGE_OPTS="$NATIVE_IMAGE_OPTS --gc=epsilon -H:-GenLoopSafepoints"

# Uncomment the following line for outputting the compiler graph to the IdealGraphVisualizer
# NATIVE_IMAGE_OPTS="$NATIVE_IMAGE_OPTS -H:MethodFilter=CalculateAverage_thomaswue.* -H:Dump=:2 -H:PrintGraph=Network"

native-image $NATIVE_IMAGE_OPTS -cp target/average-1.0.0-SNAPSHOT.jar -o target/CalculateAverage_thomaswue_image dev.morling.onebrc.CalculateAverage_thomaswue
fi
234 changes: 100 additions & 134 deletions src/main/java/dev/morling/onebrc/CalculateAverage_thomaswue.java
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Original file line number Diff line number Diff line change
Expand Up @@ -27,9 +27,7 @@
* split into 3 parts and cursors for each of those parts are processing the segment simultaneously in the same thread.
* Results are accumulated into {@link Result} objects and a tree map is used to sequentially accumulate the results in
* the end.
*
* Runs in 0.40s on an Intel i9-13900K.
*
* Runs in 0.39s on an Intel i9-13900K.
* Credit:
* Quan Anh Mai for branchless number parsing code
* Alfonso² Peterssen for suggesting memory mapping with unsafe and the subprocess idea
Expand Down Expand Up @@ -103,61 +101,123 @@ private static TreeMap<String, Result> accumulateResults(List<Result>[] allResul
return result;
}

private static Result findResult(long initialWord, long initialPos, Scanner scanner, Result[] results, List<Result> collectedResults) {
private static void parseLoop(AtomicLong counter, long fileEnd, long fileStart, List<Result> collectedResults) {
Result[] results = new Result[HASH_TABLE_SIZE];
while (true) {
long current = counter.addAndGet(SEGMENT_SIZE) - SEGMENT_SIZE;
if (current >= fileEnd) {
return;
}

long segmentEnd = nextNewLine(Math.min(fileEnd - 1, current + SEGMENT_SIZE));
long segmentStart;
if (current == fileStart) {
segmentStart = current;
}
else {
segmentStart = nextNewLine(current) + 1;
}

long dist = (segmentEnd - segmentStart) / 3;
long midPoint1 = nextNewLine(segmentStart + dist);
long midPoint2 = nextNewLine(segmentStart + dist + dist);

Scanner scanner1 = new Scanner(segmentStart, midPoint1);
Scanner scanner2 = new Scanner(midPoint1 + 1, midPoint2);
Scanner scanner3 = new Scanner(midPoint2 + 1, segmentEnd);
while (true) {
if (!scanner1.hasNext()) {
break;
}
if (!scanner2.hasNext()) {
break;
}
if (!scanner3.hasNext()) {
break;
}
long word1 = scanner1.getLong();
long word2 = scanner2.getLong();
long word3 = scanner3.getLong();
long delimiterMask1 = findDelimiter(word1);
long delimiterMask2 = findDelimiter(word2);
long delimiterMask3 = findDelimiter(word3);
Result existingResult1 = findResult(word1, delimiterMask1, scanner1, results, collectedResults);
Result existingResult2 = findResult(word2, delimiterMask2, scanner2, results, collectedResults);
Result existingResult3 = findResult(word3, delimiterMask3, scanner3, results, collectedResults);
long number1 = scanNumber(scanner1);
long number2 = scanNumber(scanner2);
long number3 = scanNumber(scanner3);
record(existingResult1, number1);
record(existingResult2, number2);
record(existingResult3, number3);
}

while (scanner1.hasNext()) {
long word = scanner1.getLong();
long pos = findDelimiter(word);
record(findResult(word, pos, scanner1, results, collectedResults), scanNumber(scanner1));
}
while (scanner2.hasNext()) {
long word = scanner2.getLong();
long pos = findDelimiter(word);
record(findResult(word, pos, scanner2, results, collectedResults), scanNumber(scanner2));
}
while (scanner3.hasNext()) {
long word = scanner3.getLong();
long pos = findDelimiter(word);
record(findResult(word, pos, scanner3, results, collectedResults), scanNumber(scanner3));
}
}
}

private static Result findResult(long initialWord, long initialDelimiterMask, Scanner scanner, Result[] results, List<Result> collectedResults) {
Result existingResult;
long word = initialWord;
long pos = initialPos;
long delimiterMask = initialDelimiterMask;
long hash;
long nameAddress = scanner.pos();

// Search for ';', one long at a time. There are two common cases that a specially treated:
// (b) the ';' is found in the first 16 bytes
if (pos != 0) {
if (delimiterMask != 0) {
// Special case for when the ';' is found in the first 8 bytes.
pos = Long.numberOfTrailingZeros(pos) >>> 3;
scanner.add(pos);
word = mask(word, pos);
int trailingZeros = Long.numberOfTrailingZeros(delimiterMask);
word = (word << (63 - trailingZeros));
scanner.add(trailingZeros >>> 3);
hash = word;

int index = hashToIndex(hash, results);
existingResult = results[index];

existingResult = results[hashToIndex(hash, results)];
if (existingResult != null && existingResult.lastNameLong == word) {
return existingResult;
}
scanner.setPos(nameAddress + pos);
}
else {
// Special case for when the ';' is found in bytes 9-16.
scanner.add(8);
hash = word;
long prevWord = word;
scanner.add(8);
word = scanner.getLong();
pos = findDelimiter(word);
if (pos != 0) {
pos = Long.numberOfTrailingZeros(pos) >>> 3;
scanner.add(pos);
word = mask(word, pos);
delimiterMask = findDelimiter(word);
if (delimiterMask != 0) {
int trailingZeros = Long.numberOfTrailingZeros(delimiterMask);
word = (word << (63 - trailingZeros));
scanner.add(trailingZeros >>> 3);
hash ^= word;
int index = hashToIndex(hash, results);
existingResult = results[index];

existingResult = results[hashToIndex(hash, results)];
if (existingResult != null && existingResult.lastNameLong == word && existingResult.secondLastNameLong == prevWord) {
return existingResult;
}
scanner.setPos(nameAddress + pos + 8);
}
else {
// Slow-path for when the ';' could not be found in the first 16 bytes.
scanner.add(8);
hash ^= word;
while (true) {
word = scanner.getLong();
pos = findDelimiter(word);
if (pos != 0) {
pos = Long.numberOfTrailingZeros(pos) >>> 3;
scanner.add(pos);
word = mask(word, pos);
delimiterMask = findDelimiter(word);
if (delimiterMask != 0) {
int trailingZeros = Long.numberOfTrailingZeros(delimiterMask);
word = (word << (63 - trailingZeros));
scanner.add(trailingZeros >>> 3);
hash ^= word;
break;
}
Expand Down Expand Up @@ -204,7 +264,8 @@ private static Result findResult(long initialWord, long initialPos, Scanner scan
private static long nextNewLine(long prev) {
while (true) {
long currentWord = Scanner.UNSAFE.getLong(prev);
long pos = findNewLine(currentWord);
long input = currentWord ^ 0x0A0A0A0A0A0A0A0AL;
long pos = (input - 0x0101010101010101L) & ~input & 0x8080808080808080L;
if (pos != 0) {
prev += Long.numberOfTrailingZeros(pos) >>> 3;
break;
Expand All @@ -216,87 +277,11 @@ private static long nextNewLine(long prev) {
return prev;
}

// Main parse loop.
private static Result[] parseLoop(AtomicLong counter, long fileEnd, long fileStart, List<Result> collectedResults) {
Result[] results = new Result[HASH_TABLE_SIZE];

while (true) {
long current = counter.addAndGet(SEGMENT_SIZE) - SEGMENT_SIZE;

if (current >= fileEnd) {
return results;
}

long segmentEnd = nextNewLine(Math.min(fileEnd - 1, current + SEGMENT_SIZE));
long segmentStart;
if (current == fileStart) {
segmentStart = current;
}
else {
segmentStart = nextNewLine(current) + 1;
}

long dist = (segmentEnd - segmentStart) / 3;
long midPoint1 = nextNewLine(segmentStart + dist);
long midPoint2 = nextNewLine(segmentStart + dist + dist);

Scanner scanner1 = new Scanner(segmentStart, midPoint1);
Scanner scanner2 = new Scanner(midPoint1 + 1, midPoint2);
Scanner scanner3 = new Scanner(midPoint2 + 1, segmentEnd);
while (true) {
if (!scanner1.hasNext()) {
break;
}
if (!scanner2.hasNext()) {
break;
}
if (!scanner3.hasNext()) {
break;
}

long word1 = scanner1.getLong();
long word2 = scanner2.getLong();
long word3 = scanner3.getLong();
long pos1 = findDelimiter(word1);
long pos2 = findDelimiter(word2);
long pos3 = findDelimiter(word3);
Result existingResult1 = findResult(word1, pos1, scanner1, results, collectedResults);
Result existingResult2 = findResult(word2, pos2, scanner2, results, collectedResults);
Result existingResult3 = findResult(word3, pos3, scanner3, results, collectedResults);
long number1 = scanNumber(scanner1);
long number2 = scanNumber(scanner2);
long number3 = scanNumber(scanner3);
record(existingResult1, number1);
record(existingResult2, number2);
record(existingResult3, number3);
}

while (scanner1.hasNext()) {
long word = scanner1.getLong();
long pos = findDelimiter(word);
record(findResult(word, pos, scanner1, results, collectedResults), scanNumber(scanner1));
}

while (scanner2.hasNext()) {
long word = scanner2.getLong();
long pos = findDelimiter(word);
record(findResult(word, pos, scanner2, results, collectedResults), scanNumber(scanner2));
}

while (scanner3.hasNext()) {
long word = scanner3.getLong();
long pos = findDelimiter(word);
record(findResult(word, pos, scanner3, results, collectedResults), scanNumber(scanner3));
}
}
}

private static long scanNumber(Scanner scanPtr) {
scanPtr.add(1);
long numberWord = scanPtr.getLong();
int decimalSepPos = Long.numberOfTrailingZeros(~numberWord & 0x10101000);
long numberWord = scanPtr.getLongAt(scanPtr.pos() + 1);
int decimalSepPos = Long.numberOfTrailingZeros(~numberWord & 0x10101000L);
long number = convertIntoNumber(decimalSepPos, numberWord);
scanPtr.add((decimalSepPos >>> 3) + 3);
scanPtr.add((decimalSepPos >>> 3) + 4);
return number;
}

Expand All @@ -316,10 +301,6 @@ private static int hashToIndex(long hash, Result[] results) {
return (int) (hashAsInt & (results.length - 1));
}

private static long mask(long word, long pos) {
return (word << ((7 - pos) << 3));
}

// Special method to convert a number in the ascii number into an int without branches created by Quan Anh Mai.
private static long convertIntoNumber(int decimalSepPos, long numberWord) {
int shift = 28 - decimalSepPos;
Expand All @@ -337,14 +318,7 @@ private static long convertIntoNumber(int decimalSepPos, long numberWord) {

private static long findDelimiter(long word) {
long input = word ^ 0x3B3B3B3B3B3B3B3BL;
long tmp = (input - 0x0101010101010101L) & ~input & 0x8080808080808080L;
return tmp;
}

private static long findNewLine(long word) {
long input = word ^ 0x0A0A0A0A0A0A0A0AL;
long tmp = (input - 0x0101010101010101L) & ~input & 0x8080808080808080L;
return tmp;
return (input - 0x0101010101010101L) & ~input & 0x8080808080808080L;
}

private static Result newEntry(Result[] results, long nameAddress, int hash, int nameLength, Scanner scanner, List<Result> collectedResults) {
Expand All @@ -357,14 +331,13 @@ private static Result newEntry(Result[] results, long nameAddress, int hash, int
r.secondLastNameLong = scanner.getLongAt(nameAddress + i - 8);
}
int remainingShift = (64 - (nameLength + 1 - i) << 3);
long lastWord = (scanner.getLongAt(nameAddress + i) << remainingShift);
r.lastNameLong = lastWord;
r.lastNameLong = (scanner.getLongAt(nameAddress + i) << remainingShift);
r.nameAddress = nameAddress;
collectedResults.add(r);
return r;
}

private static class Result {
private static final class Result {
long lastNameLong, secondLastNameLong;
short min, max;
int count;
Expand Down Expand Up @@ -409,9 +382,10 @@ public String calcName() {
}
}

private static class Scanner {
private static final class Scanner {
private static final sun.misc.Unsafe UNSAFE = initUnsafe();
private long pos, end;
private long pos;
private final long end;

private static sun.misc.Unsafe initUnsafe() {
try {
Expand Down Expand Up @@ -452,13 +426,5 @@ long getLongAt(long pos) {
byte getByteAt(long pos) {
return UNSAFE.getByte(pos);
}

long getLongAt(long pos, long[] array) {
return UNSAFE.getLong(array, pos + sun.misc.Unsafe.ARRAY_LONG_BASE_OFFSET);
}

void setPos(long l) {
this.pos = l;
}
}
}

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