Set --quota-backend-bytes when launching etcd in tests.

By default, etcd makes a huge 10 GB mmap() allocation when it starts up.
It doesn't actually use that much memory, it's just address space, but
it caused me grief when I tried to use 'rr' to debug a python test run.
Apparently, when you replay the 'rr' trace, it does allocate memory for
all that address space.

The size of the initial mmap depends on the --quota-backend-bytes setting.
Our etcd clusters are very small, so let's set --quota-backend-bytes to
keep the virtual memory size small, to make debugging with 'rr' easier.

See https://github.com/etcd-io/etcd/issues/7910 and
5e4b008106

control_plane/src/etcd.rs

@@ -48,6 +48,10 @@ pub fn start_etcd_process(env: &local_env::LocalEnv) -> anyhow::Result<()> {
             format!("--data-dir={}", etcd_data_dir.display()),
             format!("--listen-client-urls={client_urls}"),
             format!("--advertise-client-urls={client_urls}"),
+            // Set --quota-backend-bytes to keep the etcd virtual memory
+            // size smaller. Our test etcd clusters are very small.
+            // See https://github.com/etcd-io/etcd/issues/7910
+            "--quota-backend-bytes=100000000".to_string(),
         ])
         .stdout(Stdio::from(etcd_stdout_file))
         .stderr(Stdio::from(etcd_stderr_file))

test_runner/fixtures/zenith_fixtures.py

@@ -1893,7 +1893,11 @@ class Etcd:
                 f"--data-dir={self.datadir}",
                 f"--listen-client-urls={client_url}",
                 f"--advertise-client-urls={client_url}",
-                f"--listen-peer-urls=http://127.0.0.1:{self.peer_port}"
+                f"--listen-peer-urls=http://127.0.0.1:{self.peer_port}",
+                # Set --quota-backend-bytes to keep the etcd virtual memory
+                # size smaller. Our test etcd clusters are very small.
+                # See https://github.com/etcd-io/etcd/issues/7910
+                f"--quota-backend-bytes=100000000"
             ]
             self.handle = subprocess.Popen(args, stdout=log_file, stderr=log_file)