Remove concurrent commands warning

Summary: Concurrent commands should be safe now that we have DICE locking in place. Note that I won't land this until whatsapp/fbsource are using buckconfigs

Reviewed By: ndmitchell, krallin

Differential Revision: D39739920

fbshipit-source-id: cbe7feea5f5175fcf7482ff17250e20b5180d1ce

buck2_server/src/active_commands.rs

@@ -10,10 +10,7 @@
 use std::collections::HashSet;
 use std::sync::Mutex;
 
-use buck2_core::env_helper::EnvHelper;
 use buck2_events::trace::TraceId;
-use gazebo::dupe::Dupe;
-use itertools::Itertools;
 use once_cell::sync::Lazy;
 
 static ACTIVE_COMMANDS: Lazy<Mutex<HashSet<TraceId>>> = Lazy::new(|| Mutex::new(HashSet::new()));
@@ -30,37 +27,6 @@ pub struct ActiveCommandDropGuard {
 
 impl ActiveCommandDropGuard {
     pub fn new(trace_id: TraceId) -> Self {
-        let result = {
-            // Scope the guard so it's locked as little as possible
-            let mut active_commands = ACTIVE_COMMANDS.lock().unwrap();
-            active_commands.insert(trace_id.dupe());
-
-            if active_commands.len() > 1 {
-                Some(active_commands.clone())
-            } else {
-                None
-            }
-        };
-
-        if let Some(commands) = result {
-            static ERROR_CONCURRENT: EnvHelper<bool> = EnvHelper::new("BUCK2_ERROR_CONCURRENT");
-
-            let message = format!(
-                "Warning! Concurrent commands detected! Concurrent commands are not supported and likely results in crashes and incorrect builds.\n    Currently running commands are `{}`",
-                commands
-                    .iter()
-                    .map(|id| format!("https://www.internalfb.com/buck2/{}", id))
-                    .join(" ")
-            );
-
-            if ERROR_CONCURRENT.get_copied().ok() == Some(Some(true)) {
-                panic!("{}", message);
-            } else {
-                // we use eprintln here on purpose so that this message goes to ALL commands, since
-                // concurrent commands can affect correctness of ALL commands.
-                eprintln!("{}", message);
-            }
-        }
         Self { trace_id }
     }
 }