[AVRO-3194] [C++] Parsing avro file using `GenericDatum` results in segmentation fault

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: c++

Environment

Ubuntu on AWS EC2

Language

C++

• Assignee: Unassigned
• Reporter: Oscar Zhang
• Created: 01/Sep/21 21:23
• Updated: 02/Sep/21 19:02

Description

Hello,

I wonder what's the correct example of parsing an avro input stream into a vector of `GenericRecord`?

I am trying to parse .avro file using `GenericDatum` to store them in a vector of `GenericRecord`, but I got a segmentation fault (signal 11) when I am trying to call `datum.value()`. I am following the example here: https://stackoverflow.com/questions/55956222/how-to-read-data-from-avro-file-using-c-interface .Here is the sample code that I am writing:

std::unique_ptr<avro::InputStream> avroInputStream  = avro::istreamInputStream(retrievedFile); // `retrievedFile` is a basic_iostream from AWS S3

// get the schema file
std::stringstream schemaInput(schemaName);
avro::ValidSchema validSchema;
avro::compileJsonSchema(schemaInput, validSchema);

// read the data input stream with the given valid schema
avro::DataFileReader<avro::GenericDatum> fileReader(move(avroInputStream));
avro::GenericDatum datum(fileReader.dataSchema());
std::vector<avro::GenericRecord> recordArray;
while (fileReader.read(datum)) {
    if (datum.type() == avro::AVRO_RECORD) {
        std::cout << "[Check 1]" << std::endl;
        const avro::GenericRecord record = datum.value<avro::GenericRecord>(); // result in segmentation fault
        std::cout << "[Check 2]" << std::endl;
        recordArray.push_back(record);
    }
}

// processing the recordArray further
...

Interestingly, if instead I used the struct generated by the JSON schema to parse the avro file instead of treating everything generic, it worked just fine (I'm following the example here: https://avro.apache.org/docs/current/api/cpp/html/index.html#UsingAvroDataFiles )