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https://issues.apache.org/jira/browse/HADOOP-15429?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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John Doe updated HADOOP-15429:
------------------------------
Description:
In DataInputByteBuffer$Buffer class, the fields bidx and buffers, etc are
unsynchronized when used in read() and reset() function. In certain
circumstances, e.g., the reset() is invoked in a loop, the unsynchronized bidx
and buffers can trigger a concurrency bug.
Here is the code snippet.
{code:java}
ByteBuffer[] buffers = new ByteBuffer[0];
int bidx, pos, length;
@Override
public int read(byte[] b, int off, int len) {
if (bidx >= buffers.length) {
return -1;
}
int cur = 0;
do {
int rem = Math.min(len, buffers[bidx].remaining());
buffers[bidx].get(b, off, rem);
cur += rem;
off += rem;
len -= rem;
} while (len > 0 && ++bidx < buffers.length); //bidx is unsynchronized
pos += cur;
return cur;
}
public void reset(ByteBuffer[] buffers) {//if one thread keeps calling
reset() in a loop
bidx = pos = length = 0;
this.buffers = buffers;
for (ByteBuffer b : buffers) {
length += b.remaining();
}
}
{code}
was:
In DataInputByteBuffer$Buffer class, the fields bidx and buffers, etc are
unsynchronized when used in read() and reset() function. In certain
circumstances, e.g., the reset() is invoked in a loop, the unsynchronized bidx
and buffers triggers a concurrency bug.
Here is the code snippet.
{code:java}
ByteBuffer[] buffers = new ByteBuffer[0];
int bidx, pos, length;
@Override
public int read(byte[] b, int off, int len) {
if (bidx >= buffers.length) {
return -1;
}
int cur = 0;
do {
int rem = Math.min(len, buffers[bidx].remaining());
buffers[bidx].get(b, off, rem);
cur += rem;
off += rem;
len -= rem;
} while (len > 0 && ++bidx < buffers.length); //bidx is unsynchronized
pos += cur;
return cur;
}
public void reset(ByteBuffer[] buffers) {//if one thread keeps calling
reset() in a loop
bidx = pos = length = 0;
this.buffers = buffers;
for (ByteBuffer b : buffers) {
length += b.remaining();
}
}
{code}
> unsynchronized index causes DataInputByteBuffer$Buffer.read hangs
> -----------------------------------------------------------------
>
> Key: HADOOP-15429
> URL: https://issues.apache.org/jira/browse/HADOOP-15429
> Project: Hadoop Common
> Issue Type: Bug
> Components: io
> Affects Versions: 0.23.0
> Reporter: John Doe
> Priority: Minor
>
> In DataInputByteBuffer$Buffer class, the fields bidx and buffers, etc are
> unsynchronized when used in read() and reset() function. In certain
> circumstances, e.g., the reset() is invoked in a loop, the unsynchronized
> bidx and buffers can trigger a concurrency bug.
> Here is the code snippet.
> {code:java}
> ByteBuffer[] buffers = new ByteBuffer[0];
> int bidx, pos, length;
> @Override
> public int read(byte[] b, int off, int len) {
> if (bidx >= buffers.length) {
> return -1;
> }
> int cur = 0;
> do {
> int rem = Math.min(len, buffers[bidx].remaining());
> buffers[bidx].get(b, off, rem);
> cur += rem;
> off += rem;
> len -= rem;
> } while (len > 0 && ++bidx < buffers.length); //bidx is unsynchronized
> pos += cur;
> return cur;
> }
> public void reset(ByteBuffer[] buffers) {//if one thread keeps calling
> reset() in a loop
> bidx = pos = length = 0;
> this.buffers = buffers;
> for (ByteBuffer b : buffers) {
> length += b.remaining();
> }
> }
> {code}
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