Ted Yu created BEAM-1831:
----------------------------
Summary: Checking of containment in createdTables may have race
condition in StreamingWriteFn
Key: BEAM-1831
URL: https://issues.apache.org/jira/browse/BEAM-1831
Project: Beam
Issue Type: Bug
Components: runner-dataflow
Reporter: Ted Yu
Assignee: Davor Bonaci
Priority: Minor
{code}
public TableReference getOrCreateTable(BigQueryOptions options, String
tableSpec)
throws InterruptedException, IOException {
TableReference tableReference = BigQueryHelpers.parseTableSpec(tableSpec);
if (createDisposition != createDisposition.CREATE_NEVER
&& !createdTables.contains(tableSpec)) {
synchronized (createdTables) {
// Another thread may have succeeded in creating the table in the
meanwhile, so
// check again. This check isn't needed for correctness, but we add it
to prevent
// every thread from attempting a create and overwhelming our BigQuery
quota.
DatasetService datasetService = bqServices.getDatasetService(options);
if (!createdTables.contains(tableSpec)) {
{code}
The first createdTables.contains() check is outside synchronized block.
At least createdTables should be declared volatile for the double checked
locking to work.
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