Feature #14426: [PATCH] openssl: reduce memory allocation in OpenSSL::Buffering#do_write

• Status: Closed
• Assignee: rhenium (Kazuki Yamaguchi)
• Target version: -

[janko (Janko Marohnić)]

When writing data to an SSLSocket, there are a lot of, in my opinion, unnecessary strings being allocated, concretely in OpenSSL::Buffering#do_write.

When the buffer would be written, it would always be copied into a new string first, regardless of whether the write was partial or not. And in case of partial writes, it's not necessary to create copies of remaining data, we could just use the String[from, length] = "" trick immediately which modifies the string in-place.

I also thought that splitting writes on newlines was adding unnecessary memory allocations, so I removed that.

I tested uploading a 5MB file using HTTP.rb, and memory allocation went from 7.7 MB to 0.2 MB with this change.

require "http"
require "memory_profiler"
require "stringio"

body = StringIO.new("a" * 5*1024*1024)

MemoryProfiler.report do
  HTTP.post("https://example.com", body: body)
end.pretty_print

[normalperson (Eric Wong)]

[e-mail] wrote:

https://bugs.ruby-lang.org/issues/14426

I also thought that splitting writes on newlines was adding
unnecessary memory allocations, so I removed that.

Agreed.

I tested uploading a 5MB file using HTTP.rb, and memory
allocation went from 7.7 MB to 0.2 MB with this change.

Nice! This patch looks good to me, thanks.

[hsbt (Hiroshi SHIBATA)]

• Status changed from Open to Assigned
• Assignee set to rhenium (Kazuki Yamaguchi)

[janko (Janko Marohnić)]

Any updates on this one? I think it would be nice to have this included in the next patch version. This will make memory usage during large file uploads consistent regardless of whether it's going to HTTP or HTTPS endpoint; currently uploads over HTTPS consume a lot more memory, while HTTP uploads don't really allocate extra memory.

[janko (Janko Marohnić)]

• File openssl-memory-allocation.patch added
• File deleted (openssl-memory-allocation.patch)

[janko (Janko Marohnić)]

• File deleted (openssl-memory-allocation.patch)

[janko (Janko Marohnić)]

• File openssl-memory-allocation.patch openssl-memory-allocation.patch added

The patch got outdated in the latest trunk, so I updated it again. It's a really small change with big impact on memory usage when uploading files.

[rhenium (Kazuki Yamaguchi)]

• Status changed from Assigned to Closed

The patch is now in ruby/openssl (upstream)'s master branch and Ruby trunk.

For the record, the GitHub Pull Requests are:

https://github.com/ruby/ruby/pull/1924
https://github.com/ruby/openssl/pull/212