We've found a corruption which occurs when several threads do a
database dump (using "SCRIPT TO") command at the same time.
We've traced it to the class org.h2.tools.CompressTool - it uses a
shared buffer (byte[] cachedBuffer) without proper synchronization in
"public byte[] compress(byte[] in, String algorithm)".
Attached patch fixes this problem (and speeds up parallel dumps as a
nice side effect):
Index: CompressTool.java
===================================================================
--- CompressTool.java (revision 2028)
+++ CompressTool.java (working copy)
@@ -25,7 +25,6 @@
import org.h2.compress.LZFInputStream;
import org.h2.compress.LZFOutputStream;
import org.h2.constant.ErrorCode;
-import org.h2.engine.Constants;
import org.h2.message.Message;
import org.h2.util.MemoryUtils;
import org.h2.util.StringUtils;
@@ -36,8 +35,6 @@
public class CompressTool {
private static final CompressTool INSTANCE = new CompressTool();
- private static final int MAX_BUFFER_SIZE = 3 *
Constants.IO_BUFFER_SIZE_COMPRESS;
- private byte[] cachedBuffer;
private CompressTool() {
// don't allow construction
@@ -77,7 +74,7 @@
algorithm = "NO";
}
Compressor compress = getCompressor(algorithm);
- byte[] buff = getBuffer((len < 100 ? len + 100 : len) * 2);
+ byte[] buff = MemoryUtils.newBytes((len < 100 ? len + 100 :
len) * 2);
int newLen = compress(in, in.length, compress, buff);
byte[] out = MemoryUtils.newBytes(newLen);
System.arraycopy(buff, 0, out, 0, newLen);
@@ -87,7 +84,7 @@
/**
* INTERNAL
*/
- public synchronized int compress(byte[] in, int len, Compressor
compress, byte[] out) {
+ public int compress(byte[] in, int len, Compressor compress, byte
[] out) {
int newLen = 0;
out[0] = (byte) compress.getAlgorithm();
int start = 1 + writeInt(out, 1, len);
--
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