Check out my new course Learn you some Lambda best practice for great good! and learn the best practices for performance, cost, security, resilience, observability and scalability.
When you’re using the Amazon S3 client, have you come across the occasional exception that says something like one of these exception messages:
“The request was aborted: The connection was closed unexpectedly”
“Unable to read data from the transport connection: A blocking operation was interrupted by a call to WSACancelBlockingCall”
“Unable to read data from the transport connection: An established connection was aborted by the software in your host machine “
If you do, then you’re probably attempting to return the response stream directly back to the rest of your application with something like this:
However, because the stream is coming from the Amazon S3 service and is fed to your code in chunks, your code needs to ensure that the connection to S3 stays open until all the data has been received. So as mentioned in the S3 documentation (which incidentally, most of us don’t read in great details…) here, you should be wrapping the response you get from the GetObject method in a using clause.
Depends on what it is you want to do with the stream, you might have to handle it differently. For instance, if you just want to read the string content of a text file, you might want to do this:
Alternatively, if you want to return the response stream itself, you’ll need to first load the stream in its entirety and return the loaded stream. Unfortunately, at the time of this writing, the AWSSDK library still hasn’t been migrated to .Net 4 and therefore doesn’t have the uber useful CopyTo method added in .Net 4, so you will most likely have to do the heavy lifting yourself and read the data out manually into a memory stream:
I specialise in rapidly transitioning teams to serverless and building production-ready services on AWS.
Are you struggling with serverless or need guidance on best practices? Do you want someone to review your architecture and help you avoid costly mistakes down the line? Whatever the case, I’m here to help.
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Here is a complete list of all my posts on serverless and AWS Lambda. In the meantime, here are a few of my most popular blog posts.
- Lambda optimization tip – enable HTTP keep-alive
- You are thinking about serverless costs all wrong
- Many faced threats to Serverless security
- We can do better than percentile latencies
- I’m afraid you’re thinking about AWS Lambda cold starts all wrong
- Yubl’s road to Serverless
- AWS Lambda – should you have few monolithic functions or many single-purposed functions?
- AWS Lambda – compare coldstart time with different languages, memory and code sizes
- Guys, we’re doing pagination wrong