How to use

Mutex

in

async-mutex

const writeLog = log => {
 mutex
  .acquire()
  .then(function(release) {
   let fileLog=`-----------------------------------------------------------\n`+log+`\n`;
   fs.appendFile("_logs/" + logName, fileLog, function(err) {
    if (err) throw err;
    release();
   });
  })
 
}

/**
  * Append a single row to the parquet file. Rows are buffered in memory until
  * rowGroupSize rows are in the buffer or close() is called
  */
 async appendRow(row) {
  if (this.closed) {
   throw 'writer was closed';
  }

  const release = await this.writeMutex.acquire();

  try {
   parquet_shredder.shredRecord(this.schema, row, this.rowBuffer);

   if (this.rowBuffer.rowCount >= this.rowGroupSize) {
    await this.envelopeWriter.writeRowGroup(this.rowBuffer);
    this.rowBuffer = {};
   }
  } finally {
    release();
  }
 }

const release = await this.writeMutex.acquire();