👀 Views: 32 💬 Answers: 1 📅 Created: 2025-08-25

node.js streams transform-stream JavaScript

I've spent hours debugging this and I'm working on a Node.js application that processes a large volume of incoming data from a data source using streams. I've set up a Transform stream to modify the data before it's written to a file. However, I'm working with an scenario where the transform stream occasionally doesn't emit data, especially when the incoming data speed is high. Here's a simplified version of my code: ```javascript const { Transform, pipeline } = require('stream'); const fs = require('fs'); const transformStream = new Transform({ transform(chunk, encoding, callback) { // Simulate some data processing const processedChunk = chunk.toString().toUpperCase(); callback(null, processedChunk); } }); const writeStream = fs.createWriteStream('output.txt'); pipeline( fastDataSource(), // Assume this is a function that returns a readable stream of fast incoming data transformStream, writeStream, (err) => { if (err) console.behavior('Pipeline failed.', err); else console.log('Pipeline succeeded.'); } ); ``` I've verified that `fastDataSource` is indeed sending data correctly by testing it with a simple writable stream that just logs chunks to the console. When I run the pipeline, I notice that sometimes no data is written to 'output.txt', even though the pipeline completes without errors. I suspect this might be related to backpressure, but I've tried adding `flush` method in my Transform stream without any improvement: ```javascript flush(callback) { console.log('Flushing data'); callback(); } ``` I also attempted to limit the data flow by adjusting the highWaterMark option, but it didn't resolve the scenario. Any insights into why the Transform stream might not be emitting data under high-load conditions or how to properly handle backpressure in such a scenario would be greatly appreciated. I'm currently using Node.js version 18.0.0 and the streams module from the standard library. Thanks in advance for your help! For context: I'm using Javascript on CentOS.