[tor-project] What's happening in Shadow 2022-06

[Jim Newsome]

Mirrored from https://github.com/shadow/shadow/discussions/2243

This is part of a series of periodic updates of development in Shadow. 
This work is sponsored by the NSF.

NSF sponsorship: https://shadow.github.io/docs/guide/nsf_sponsorship.html
Previous update: https://github.com/shadow/shadow/discussions/2007

We will be presenting a paper on Shadow's 2.0 architecture, "Co-opting 
Linux Processes for High-Performance Network Simulation", at the USENIX 
Annual Technical Conference.

Paper: https://www.robgjansen.com/publications/phantom-atc2022.pdf
USENIX ATC: https://www.usenix.org/conference/atc22

We've merged 123 non-dependabot pull requests and closed 38 issues 
since our previous update.

Pull requests: 
https://github.com/shadow/shadow/pulls?q=is%3Apr+merged%3A2022-04-05..2022-07-27+-author%3Aapp%2Fdependabot+
Issues: 
https://github.com/shadow/shadow/issues?q=closed%3A2022-04-05..2022-06-27+is%3Aissue+

Release status
==============

We have released Shadow 2.1. This release focused largely on more 
complete and accurate OS emulation, to increase the number of 
applications that can be run under Shadow. Shadow now supports newer 
versions of glibc, software that uses signals and "busy loops", and 
dynamically linked golang programs. It also has a new `--debug-hosts` 
feature to facilitate attaching debuggers like `gdb` to Shadow's managed 
processes. See the release notes for details.

Shadow 2.1: https://github.com/shadow/shadow/releases/tag/v2.1.0
Release notes: https://github.com/shadow/shadow/discussions/2219

We've begun work on Shadow 2.2, which will largely be a push to refactor 
and migrate more of the core Shadow code to Rust, which is expected to 
ultimately increase velocity of Shadow development.

Shadow 2.2 project: https://github.com/shadow/shadow/projects/6

Notable changes since last update
=============================

Most of the changes since the last update are covered in the v2.1.0 
release notes. We are now also keeping a running CHANGELOG of
user-facing changes since the last release. Currently this is:

* We have removed ptrace-mode, and the associated experimental options 
`use-o-n-waitpid-workaround` and `--interpose-method`. ptrace-mode was 
an alternative to Shadow's current interposition mechanism that uses 
`LD_PRELOAD` and `seccomp`. This change should be transparent to most 
users, since it hasn't been the default for several releases, and was 
only accessible via experimental options. See 
https://github.com/shadow/shadow/issues/1945

Release notes: https://github.com/shadow/shadow/discussions/2219
Changelog: https://github.com/shadow/shadow/blob/main/CHANGELOG

Happy simulating!
The Shadow team