Created
March 4, 2016 10:54
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Writing to a very very large file - performance test
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import java.io.BufferedWriter; | |
import java.io.File; | |
import java.io.FileWriter; | |
import java.io.IOException; | |
import java.io.Writer; | |
import java.util.ArrayList; | |
import java.util.List; | |
public class FileWritingPerfTest { | |
private static final int ITERATIONS = 5; | |
private static final double MEG = (Math.pow(1024, 2)); | |
private static final int RECORD_COUNT = 4000000; | |
private static final String RECORD = "Help I am trapped in a fortune cookie factory\n"; | |
private static final int RECSIZE = RECORD.getBytes().length; | |
public static void main(String[] args) throws Exception { | |
List<String> records = new ArrayList<String>(RECORD_COUNT); | |
int size = 0; | |
for (int i = 0; i < RECORD_COUNT; i++) { | |
records.add(RECORD); | |
size += RECSIZE; | |
} | |
System.out.println(records.size() + " 'records'"); | |
System.out.println(size / MEG + " MB"); | |
for (int i = 0; i < ITERATIONS; i++) { | |
System.out.println("\nIteration " + i); | |
writeRaw(records); | |
writeBuffered(records, 8192); | |
writeBuffered(records, (int) MEG); | |
writeBuffered(records, 4 * (int) MEG); | |
} | |
} | |
private static void writeRaw(List<String> records) throws IOException { | |
File file = File.createTempFile("foo", ".txt"); | |
try { | |
FileWriter writer = new FileWriter(file); | |
System.out.print("Writing raw... "); | |
write(records, writer); | |
} finally { | |
// comment this out if you want to inspect the files afterward | |
file.delete(); | |
} | |
} | |
private static void writeBuffered(List<String> records, int bufSize) throws IOException { | |
File file = File.createTempFile("foo", ".txt"); | |
try { | |
FileWriter writer = new FileWriter(file); | |
BufferedWriter bufferedWriter = new BufferedWriter(writer, bufSize); | |
System.out.print("Writing buffered (buffer size: " + bufSize + ")... "); | |
write(records, bufferedWriter); | |
} finally { | |
// comment this out if you want to inspect the files afterward | |
file.delete(); | |
} | |
} | |
private static void write(List<String> records, Writer writer) throws IOException { | |
long start = System.currentTimeMillis(); | |
for (String record: records) { | |
writer.write(record); | |
} | |
writer.flush(); | |
writer.close(); | |
long end = System.currentTimeMillis(); | |
System.out.println((end - start) / 1000f + " seconds"); | |
} | |
} |
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