Parquet pages for different columns cannot be read in parallel

All ColumnChunkPageReader instances use the same decompressor. 

```java

BytesInputDecompressor decompressor = options.getCodecFactory().getDecompressor(descriptor.metadata.getCodec());
return new ColumnChunkPageReader(decompressor, pagesInChunk, dictionaryPage);
```
The CodecFactory caches the decompressors for every codec type returning the same instance on every getCompressor(codecName) call. See the caching happening here:

```java

@Override
public BytesDecompressor getDecompressor(CompressionCodecName codecName) {
BytesDecompressor decomp = decompressors.get(codecName);
if (decomp == null){
decomp = createDecompressor(codecName); decompressors.put(codecName, decomp);
}
return decomp;
}
 
```
 

If multiple threads try to read the pages belonging to different columns, they run into thread

safety issues. This issue prevents increasing the throughput at which applications can read parquet data by parallelizing page reads. 

**Reporter**: [Samarth Jain](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=samarthjain) / @samarthjain
**Assignee**: [Samarth Jain](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=samarthjain) / @samarthjain
#### PRs and other links:
- [GitHub Pull Request #668](https://github.com/apache/parquet-mr/pull/668)
- [GitHub Pull Request #670](https://github.com/apache/parquet-mr/pull/670)

_{**Note**: *This issue was originally created as [PARQUET-1641](https://issues.apache.org/jira/browse/PARQUET-1641). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

Comienza con ParquetFileReader.java alrededor de la línea 1286 y CodecFactory.java alrededor de la línea 197 para rastrear cómo comparten los descompresores las instancias de ColumnChunkPageReader. Revisa los pull requests #668 y #670 antes de empezar y, después, verifica que las lecturas de páginas para distintas columnas puedan ejecutarse en paralelo sin el problema de seguridad de hilos informado.

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