feat(spooler): Add configuration check based on memory size

CHANGELOG.md

@@ -24,6 +24,7 @@
 - Expose runtime utilization metric in autoscaler endpoint. ([#4606](https://github.com/getsentry/relay/pull/4606))
 - Bump the revision of `sysinfo` to the revision at `15b3be3273ba286740122fed7bb7dccd2a79dc8f`. ([#4613](https://github.com/getsentry/relay/pull/4613))
 - Switch the processor and store to `async`. ([#4552](https://github.com/getsentry/relay/pull/4552))
+- Validate the spooling memory configuration on startup. ([#4617](https://github.com/getsentry/relay/pull/4617))
 
 ## 25.3.0
 

relay-server/src/utils/memory.rs

@@ -77,6 +77,12 @@ impl MemoryStat {
         }))
     }
 
+    /// Returns the current memory data without instantiating [`MemoryStat`].
+    pub fn current_memory() -> Memory {
+        let mut system = System::new();
+        Self::refresh_memory(&mut system)
+    }
+
     /// Returns a copy of the most up-to-date memory data.
     pub fn memory(&self) -> Memory {
         self.try_update();
@@ -103,6 +109,18 @@ impl MemoryStat {
         memory
     }
 
+    /// Updates the memory readings unconditionally.
+    fn update(&self) {
+        let mut system = self
+            .0
+            .system
+            .lock()
+            .unwrap_or_else(|system| system.into_inner());
+
+        let updated_memory = Self::refresh_memory(&mut system);
+        self.0.memory.store(Arc::new(updated_memory));
+    }
+
     /// Updates the memory readings if at least `refresh_frequency_ms` has passed.
     fn try_update(&self) {
         let last_update = self.0.last_update.load(Ordering::Relaxed);
@@ -126,14 +144,7 @@ impl MemoryStat {
             return;
         }
 
-        let mut system = self
-            .0
-            .system
-            .lock()
-            .unwrap_or_else(|system| system.into_inner());
-
-        let updated_memory = Self::refresh_memory(&mut system);
-        self.0.memory.store(Arc::new(updated_memory));
+        self.update();
     }
 }
 

relay/src/setup.rs

@@ -2,6 +2,32 @@
 use anyhow::Context;
 use anyhow::Result;
 use relay_config::{Config, RelayMode};
+use relay_server::MemoryStat;
+
+/// Validates that the `batch_size_bytes` of the configuration is correct and doesn't lead to
+/// deadlocks in the buffer.
+fn assert_batch_size_bytes(config: &Config) -> Result<()> {
+    // We create a temporary memory reading used just for the config check.
+    let memory = MemoryStat::current_memory();
+
+    // We expect the batch size for the spooler to be 10% of the memory threshold over which the
+    // buffer stops unspooling.
+    //
+    // The 10% threshold was arbitrarily chosen to give the system leeway when spooling.
+    let configured_batch_size_bytes = config.spool_envelopes_batch_size_bytes() as f32;
+    let maximum_batch_size_bytes =
+        memory.total as f32 * config.spool_max_backpressure_memory_percent() * 0.1;
+
+    if configured_batch_size_bytes > maximum_batch_size_bytes {
+        anyhow::bail!(
+            "the configured `spool.envelopes.batch_size_bytes` is {} bytes but it must be <= than {} bytes",
+            configured_batch_size_bytes,
+            maximum_batch_size_bytes
+        )
+    }
+
+    Ok(())
+}
 
 pub fn check_config(config: &Config) -> Result<()> {
     if config.relay_mode() == RelayMode::Managed && config.credentials().is_none() {
@@ -31,6 +57,8 @@ pub fn check_config(config: &Config) -> Result<()> {
         }
     }
 
+    assert_batch_size_bytes(config)?;
+
     Ok(())
 }
 

tests/integration/test_basic.py

@@ -85,6 +85,38 @@ def get_project_config():
     conn.close()
 
 
+def test_batch_size_bytes_asserted(mini_sentry, relay):
+    from time import sleep
+
+    # Create a temporary directory for the sqlite db.
+    db_file_path = os.path.join(tempfile.mkdtemp(), "database.db")
+
+    get_project_config_original = mini_sentry.app.view_functions["get_project_config"]
+
+    @mini_sentry.app.endpoint("get_project_config")
+    def get_project_config():
+        sleep(1)  # Causes the process to wait for one second before shutting down
+        return get_project_config_original()
+
+    project_id = 42
+    mini_sentry.add_basic_project_config(project_id)
+
+    mini_sentry.fail_on_relay_error = False
+
+    relay = relay(
+        mini_sentry,
+        {
+            "limits": {"shutdown_timeout": 2},
+            # Arbitrarily chosen high value to always fail.
+            "spool": {"envelopes": {"path": db_file_path, "batch_size_bytes": "10tb"}},
+        },
+        wait_health_check=False,
+    )
+
+    # Assert that the process exited with an error (non-zero exit code)
+    assert relay.wait_for_exit() != 0, "Expected Relay to not start, but it started"
+
+
 @pytest.mark.skip("Flaky test")
 def test_forced_shutdown(mini_sentry, relay):
     from time import sleep