lamber-ken commented on a change in pull request #3243: [CARBONDATA-3401] fix the java sdk create wrong carbondata filename
URL:
https://github.com/apache/carbondata/pull/3243#discussion_r288371901
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File path: store/sdk/src/main/java/org/apache/carbondata/sdk/file/CarbonWriterBuilder.java
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@@ -580,7 +580,7 @@ private void setCsvHeader(CarbonLoadModel model) {
public CarbonLoadModel buildLoadModel(Schema carbonSchema)
throws IOException, InvalidLoadOptionException {
- timestamp = System.nanoTime();
+ timestamp = System.currentTimeMillis();
Review comment:
> in Concurrency (in same JVM multiple threads) System.currentTimeMillis() can be same , which can overwrite existing carbonfile .
Hi @BJangir, thanks for your mention about the concurrent problem. I have some points from my side.
**First**, the filename is consisted of (taskNo, batch_prefix, batchNo, bucketNumber, segmentNo, factUpdateTimestamp), I think the filename may nerver same.
**Second**, it's a wrong way to use `System.nanoTime()` to assign to the timestamp, the value returned represents nanoseconds since some fixed but arbitrary origin time (perhaps in the future, so values may be negative), so the filename may like this
```
53353670335116_batchno0-0-null--12341312341.carbonindex
part-0--100010000_batchno0-0-null--12341312341.carbondata
```
**Thrid**, from the java doc, it says the values returned by this method become meaningful only when the difference between two such values, obtained within the same instance of a Java virtual machine, is computed.
[Java Platform SE doc](
https://docs.oracle.com/javase/8/docs/api/index.html)
Please correct me if I am wrong, thanks.
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