HagaiHargil opened a new issue #646:
URL: https://github.com/apache/arrow-rs/issues/646
**Describe the bug**
When using `ipc::StreamReader`, if by any chance the stream buffer empties
and then re-fills, the current `StreamReader` will not detect the new data that
was added.
**To Reproduce**
```rust
fn test_intermittent_writing() {
// Generate mock data
let schema = Schema::new(vec![
Field::new("id", DataType::Int32, false)
]);
let second_schema = schema.clone();
std::thread::spawn(||
start_writer_and_write(String::from("test_test.d"), second_schema));
// Let the writer write something
std::thread::sleep(std::time::Duration::from_secs(1));
let mut stream =
StreamReader::try_new(File::open("test_test.d").unwrap()).unwrap();
let mut idx = 0;
// Start looping and reading the stream. The first loop detects and
prints
// out the array. No other loops detect anything, even though after
// several seconds new data appears in the stream.
while idx < 12 {
match stream.next() {
Some(x) => println!("{:?}", x),
None => println!("None"),
}
idx += 1;
std::thread::sleep(std::time::Duration::from_secs(1));
}
println!("Stopped loop, checking whether the data is there");
let mut stream =
StreamReader::try_new(File::open("test_test.d").unwrap()).unwrap();
println!("{:?}", stream.next().unwrap()); // prints the Batch
println!("{:?}", stream.next().unwrap()); // also prints the second
Batch
}
fn start_writer_and_write(stream_name: String, schema: Schema) {
let stream = File::create(stream_name).unwrap();
let mut stream = StreamWriter::try_new(stream, &schema).unwrap();
let id_array = Int32Array::from(vec![1, 2, 3, 4, 5]);
let batch = RecordBatch::try_new(
Arc::new(schema.clone()),
vec![Arc::new(id_array)]
).unwrap();
stream.write(&batch).unwrap();
std::thread::sleep(std::time::Duration::from_secs(10));
stream.write(&batch).unwrap();
println!("I wrote it, goodbye");
}
```
**Expected behavior**
From my understanding, as long as the `StreamReader` is open new data should
be detected even if the stream was empty for some time.
**Additional context**
I noticed this behavior when writing to a stream from `pyarrow`, but the
code above shows that a Rust-to-Rust version of this issue also exists.
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