From f665351740fc23308d8f9705092c37bdd14376fb Mon Sep 17 00:00:00 2001
From: Teknium <127238744+teknium1@users.noreply.github.com>
Date: Wed, 25 Mar 2026 10:56:48 -0700
Subject: [PATCH] fix(shell): exponential backoff for persistent shell polling
 (#2996)

* fix(shell): replace fixed 10ms poll interval with exponential backoff to reduce WSL2 resource consumption

* fix(shell): rename _poll_interval to _poll_interval_start for clarity, update SSH override

* fix(shell): correctly rename _poll_interval to _poll_interval_start in ssh.py

---------

Co-authored-by: ygd58 <buraysandro9@gmail.com>
---
 tools/environments/persistent_shell.py | 9 +++++++--
 tools/environments/ssh.py              | 2 +-
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/tools/environments/persistent_shell.py b/tools/environments/persistent_shell.py
index 4b89db471..b1280bf4e 100644
--- a/tools/environments/persistent_shell.py
+++ b/tools/environments/persistent_shell.py
@@ -40,7 +40,8 @@ class PersistentShellMixin:
     def _cleanup_temp_files(self): ...
 
     _session_id: str = ""
-    _poll_interval: float = 0.01
+    _poll_interval_start: float = 0.01  # initial poll interval (10ms)
+    _poll_interval_max: float = 0.25    # max poll interval (250ms) — reduces I/O for long commands
 
     @property
     def _temp_prefix(self) -> str:
@@ -224,7 +225,7 @@ class PersistentShellMixin:
         )
         self._send_to_shell(ipc_script)
         deadline = time.monotonic() + timeout
-        poll_interval = self._poll_interval
+        poll_interval = self._poll_interval_start  # starts at 10ms, backs off to 250ms
 
         while True:
             if is_interrupted():
@@ -256,6 +257,10 @@ class PersistentShellMixin:
                 break
 
             time.sleep(poll_interval)
+            # Exponential backoff: fast start (10ms) for quick commands,
+            # ramps up to 250ms for long-running commands — reduces I/O by 10-25x
+            # on WSL2 where polling keeps the VM hot and memory pressure high.
+            poll_interval = min(poll_interval * 1.5, self._poll_interval_max)
 
         output, exit_code, new_cwd = self._read_persistent_output()
         if new_cwd:
diff --git a/tools/environments/ssh.py b/tools/environments/ssh.py
index e6c6a8c1c..fa3781a99 100644
--- a/tools/environments/ssh.py
+++ b/tools/environments/ssh.py
@@ -87,7 +87,7 @@ class SSHEnvironment(PersistentShellMixin, BaseEnvironment):
         except subprocess.TimeoutExpired:
             raise RuntimeError(f"SSH connection to {self.user}@{self.host} timed out")
 
-    _poll_interval: float = 0.15
+    _poll_interval_start: float = 0.15  # SSH: higher initial interval (150ms) for network latency
 
     @property
     def _temp_prefix(self) -> str: