diff --git a/libraries/chain/controller.cpp b/libraries/chain/controller.cpp
index 4759ad7967..c2f9fe2d79 100644
--- a/libraries/chain/controller.cpp
+++ b/libraries/chain/controller.cpp
@@ -210,6 +210,12 @@ struct pending_state {
 };
 
 struct controller_impl {
+   enum class app_window_type {
+      write, // Only main thread is running; read-only threads are not running.
+             // All read-write and read-only tasks are sequentially executed.
+      read   // Main thread and read-only threads are running read-ony tasks in parallel.
+             // Read-write tasks are not being executed.
+   };
 
    // LLVM sets the new handler, we need to reset this to throw a bad_alloc exception so we can possibly exit cleanly
    // and not just abort.
@@ -251,6 +257,7 @@ struct controller_impl {
    // which overwrites the same static wasmif, is used for eosvmoc too.
    wasm_interface  wasmif;  // used by main thread and all threads for EOSVMOC
    thread_local static std::unique_ptr<wasm_interface> wasmif_thread_local; // a copy for each read-only thread, used by eos-vm and eos-vm-jit
+   app_window_type app_window = app_window_type::write;
 
    typedef pair<scope_name,action_name>                   handler_key;
    map< account_name, map<handler_key, apply_handler> >   apply_handlers;
@@ -2694,6 +2701,16 @@ struct controller_impl {
 
    bool is_on_main_thread() { return main_thread_id == std::this_thread::get_id(); };
 
+   void set_to_write_window() {
+      app_window = app_window_type::write;
+   }
+   void set_to_read_window() {
+      app_window = app_window_type::read;
+   }
+   bool is_write_window() const {
+      return app_window == app_window_type::write;
+   }
+
    wasm_interface& get_wasm_interface() {
       if ( is_on_main_thread()
 #ifdef EOSIO_EOS_VM_OC_RUNTIME_ENABLED
@@ -3687,6 +3704,16 @@ void controller::init_thread_local_data() {
    my->init_thread_local_data();
 }
 
+void controller::set_to_write_window() {
+   my->set_to_write_window();
+}
+void controller::set_to_read_window() {
+   my->set_to_read_window();
+}
+bool controller::is_write_window() const {
+   return my->is_write_window();
+}
+
 /// Protocol feature activation handlers:
 
 template<>
diff --git a/libraries/chain/include/eosio/chain/controller.hpp b/libraries/chain/include/eosio/chain/controller.hpp
index 3862c27db5..799d0e4212 100644
--- a/libraries/chain/include/eosio/chain/controller.hpp
+++ b/libraries/chain/include/eosio/chain/controller.hpp
@@ -373,6 +373,9 @@ namespace eosio { namespace chain {
       void set_db_read_only_mode();
       void unset_db_read_only_mode();
       void init_thread_local_data();
+      void set_to_write_window();
+      void set_to_read_window();
+      bool is_write_window() const;
 
       private:
          friend class apply_context;
diff --git a/libraries/chain/include/eosio/chain/webassembly/eos-vm-oc/code_cache.hpp b/libraries/chain/include/eosio/chain/webassembly/eos-vm-oc/code_cache.hpp
index 48ae33afce..ef48ff14e2 100644
--- a/libraries/chain/include/eosio/chain/webassembly/eos-vm-oc/code_cache.hpp
+++ b/libraries/chain/include/eosio/chain/webassembly/eos-vm-oc/code_cache.hpp
@@ -85,9 +85,6 @@ class code_cache_base {
 
       template <typename T>
       void serialize_cache_index(fc::datastream<T>& ds);
-
-      std::thread::id _main_thread_id;
-      bool is_main_thread() const;
 };
 
 class code_cache_async : public code_cache_base {
@@ -98,7 +95,7 @@ class code_cache_async : public code_cache_base {
       //If code is in cache: returns pointer & bumps to front of MRU list
       //If code is not in cache, and not blacklisted, and not currently compiling: return nullptr and kick off compile
       //otherwise: return nullptr
-      const code_descriptor* const get_descriptor_for_code(const digest_type& code_id, const uint8_t& vm_version);
+      const code_descriptor* const get_descriptor_for_code(const digest_type& code_id, const uint8_t& vm_version, bool is_write_window);
 
    private:
       std::thread _monitor_reply_thread;
@@ -115,7 +112,7 @@ class code_cache_sync : public code_cache_base {
       ~code_cache_sync();
 
       //Can still fail and return nullptr if, for example, there is an expected instantiation failure
-      const code_descriptor* const get_descriptor_for_code_sync(const digest_type& code_id, const uint8_t& vm_version);
+      const code_descriptor* const get_descriptor_for_code_sync(const digest_type& code_id, const uint8_t& vm_version, bool is_write_window);
 };
 
 }}}
diff --git a/libraries/chain/wasm_interface.cpp b/libraries/chain/wasm_interface.cpp
index 0899b0ec4b..481d534de8 100644
--- a/libraries/chain/wasm_interface.cpp
+++ b/libraries/chain/wasm_interface.cpp
@@ -93,7 +93,7 @@ namespace eosio { namespace chain {
       if(my->eosvmoc) {
          const chain::eosvmoc::code_descriptor* cd = nullptr;
          try {
-            cd = my->eosvmoc->cc.get_descriptor_for_code(code_hash, vm_version);
+            cd = my->eosvmoc->cc.get_descriptor_for_code(code_hash, vm_version, context.control.is_write_window());
          }
          catch(...) {
             //swallow errors here, if EOS VM OC has gone in to the weeds we shouldn't bail: continue to try and run baseline
diff --git a/libraries/chain/webassembly/runtimes/eos-vm-oc.cpp b/libraries/chain/webassembly/runtimes/eos-vm-oc.cpp
index 65227d1446..831c507b4f 100644
--- a/libraries/chain/webassembly/runtimes/eos-vm-oc.cpp
+++ b/libraries/chain/webassembly/runtimes/eos-vm-oc.cpp
@@ -28,7 +28,7 @@ class eosvmoc_instantiated_module : public wasm_instantiated_module_interface {
       bool is_main_thread() { return _main_thread_id == std::this_thread::get_id(); };
 
       void apply(apply_context& context) override {
-         const code_descriptor* const cd = _eosvmoc_runtime.cc.get_descriptor_for_code_sync(_code_hash, _vm_version);
+         const code_descriptor* const cd = _eosvmoc_runtime.cc.get_descriptor_for_code_sync(_code_hash, _vm_version, context.control.is_write_window());
          EOS_ASSERT(cd, wasm_execution_error, "EOS VM OC instantiation failed");
 
          if ( is_main_thread() )
diff --git a/libraries/chain/webassembly/runtimes/eos-vm-oc/code_cache.cpp b/libraries/chain/webassembly/runtimes/eos-vm-oc/code_cache.cpp
index 95dfec6a51..d0e49f57d0 100644
--- a/libraries/chain/webassembly/runtimes/eos-vm-oc/code_cache.cpp
+++ b/libraries/chain/webassembly/runtimes/eos-vm-oc/code_cache.cpp
@@ -107,10 +107,11 @@ std::tuple<size_t, size_t> code_cache_async::consume_compile_thread_queue() {
 }
 
 
-const code_descriptor* const code_cache_async::get_descriptor_for_code(const digest_type& code_id, const uint8_t& vm_version) {
+const code_descriptor* const code_cache_async::get_descriptor_for_code(const digest_type& code_id, const uint8_t& vm_version, bool is_write_window) {
    //if there are any outstanding compiles, process the result queue now
-   //do this only on main thread (which is in single threaded write window)
-   if(is_main_thread() && _outstanding_compiles_and_poison.size()) {
+   //When app is in write window, all tasks are running sequentially and read-only threads
+   //are not running. Safe to update cache entries.
+   if(is_write_window && _outstanding_compiles_and_poison.size()) {
       auto [count_processed, bytes_remaining] = consume_compile_thread_queue();
 
       if(count_processed)
@@ -136,11 +137,11 @@ const code_descriptor* const code_cache_async::get_descriptor_for_code(const dig
    //check for entry in cache
    code_cache_index::index<by_hash>::type::iterator it = _cache_index.get<by_hash>().find(boost::make_tuple(code_id, vm_version));
    if(it != _cache_index.get<by_hash>().end()) {
-      if (is_main_thread())
+      if (is_write_window)
          _cache_index.relocate(_cache_index.begin(), _cache_index.project<0>(it));
       return &*it;
    }
-   if(!is_main_thread()) // on read-only thread
+   if(!is_write_window)
       return nullptr;
 
    const code_tuple ct = code_tuple{code_id, vm_version};
@@ -179,15 +180,15 @@ code_cache_sync::~code_cache_sync() {
       elog("unexpected response from EOS VM OC compile monitor during shutdown");
 }
 
-const code_descriptor* const code_cache_sync::get_descriptor_for_code_sync(const digest_type& code_id, const uint8_t& vm_version) {
+const code_descriptor* const code_cache_sync::get_descriptor_for_code_sync(const digest_type& code_id, const uint8_t& vm_version, bool is_write_window) {
    //check for entry in cache
    code_cache_index::index<by_hash>::type::iterator it = _cache_index.get<by_hash>().find(boost::make_tuple(code_id, vm_version));
    if(it != _cache_index.get<by_hash>().end()) {
-      if (is_main_thread())
+      if (is_write_window)
          _cache_index.relocate(_cache_index.begin(), _cache_index.project<0>(it));
       return &*it;
    }
-   if(!is_main_thread())
+   if(!is_write_window)
       return nullptr;
 
    const code_object* const codeobject = _db.find<code_object,by_code_hash>(boost::make_tuple(code_id, 0, vm_version));
@@ -212,8 +213,7 @@ const code_descriptor* const code_cache_sync::get_descriptor_for_code_sync(const
 
 code_cache_base::code_cache_base(const boost::filesystem::path data_dir, const eosvmoc::config& eosvmoc_config, const chainbase::database& db) :
    _db(db),
-   _cache_file_path(data_dir/"code_cache.bin"),
-   _main_thread_id(std::this_thread::get_id())
+   _cache_file_path(data_dir/"code_cache.bin")
 {
    static_assert(sizeof(allocator_t) <= header_offset, "header offset intersects with allocator");
 
@@ -390,8 +390,4 @@ void code_cache_base::check_eviction_threshold(size_t free_bytes) {
    if(free_bytes < _free_bytes_eviction_threshold)
       run_eviction_round();
 }
-
-bool code_cache_base::is_main_thread() const {
-   return _main_thread_id == std::this_thread::get_id();
-}
 }}}
diff --git a/plugins/producer_plugin/producer_plugin.cpp b/plugins/producer_plugin/producer_plugin.cpp
index b6f9c60a44..0cbfd1a5df 100644
--- a/plugins/producer_plugin/producer_plugin.cpp
+++ b/plugins/producer_plugin/producer_plugin.cpp
@@ -2309,7 +2309,7 @@ producer_plugin_impl::handle_push_result( const transaction_metadata_ptr& trx,
       // Dry-run trxs only run in write window. Read-only trxs can run in
       // both write and read windows; time spent in read window is counted
       // by read window summary.
-      if ( app().executor().is_write_window() ) {
+      if ( chain.is_write_window() ) {
          auto dur = end - start;
          _time_tracker.add_fail_time(dur, trx->is_transient());
       }
@@ -2356,7 +2356,7 @@ producer_plugin_impl::handle_push_result( const transaction_metadata_ptr& trx,
       // Dry-run trxs only run in write window. Read-only trxs can run in
       // both write and read windows; time spent in read window is counted
       // by read window summary.
-      if ( app().executor().is_write_window() ) {
+      if ( chain.is_write_window() ) {
          auto dur = end - start;
          _time_tracker.add_success_time(dur, trx->is_transient());
       }
@@ -2833,9 +2833,11 @@ void producer_plugin_impl::switch_to_write_window() {
                ("t", _ro_all_threads_exec_time_us.load()));
    }
 
+   chain::controller& chain = chain_plug->chain();
+
    // this method can be called from multiple places. it is possible
    // we are already in write window.
-   if ( app().executor().is_write_window() ) {
+   if ( chain.is_write_window() ) {
       return;
    }
 
@@ -2850,6 +2852,7 @@ void producer_plugin_impl::start_write_window() {
    chain::controller& chain = chain_plug->chain();
 
    app().executor().set_to_write_window();
+   chain.set_to_write_window();
    chain.unset_db_read_only_mode();
    _idle_trx_time = _ro_window_deadline = fc::time_point::now();
 
@@ -2869,7 +2872,8 @@ void producer_plugin_impl::start_write_window() {
 
 // Called only from app thread
 void producer_plugin_impl::switch_to_read_window() {
-   EOS_ASSERT(app().executor().is_write_window(),  producer_exception, "expected to be in write window");
+   chain::controller& chain = chain_plug->chain();
+   EOS_ASSERT(chain.is_write_window(),  producer_exception, "expected to be in write window");
    EOS_ASSERT( _ro_num_active_exec_tasks.load() == 0 && _ro_exec_tasks_fut.empty(), producer_exception, "_ro_exec_tasks_fut expected to be empty" );
 
    _time_tracker.add_idle_time( fc::time_point::now() - _idle_trx_time );
@@ -2880,8 +2884,6 @@ void producer_plugin_impl::switch_to_read_window() {
       return;
    }
 
-
-   auto& chain = chain_plug->chain();
    uint32_t pending_block_num = chain.head_block_num() + 1;
    _ro_read_window_start_time = fc::time_point::now();
    _ro_window_deadline = _ro_read_window_start_time + _ro_read_window_effective_time_us;
@@ -2889,6 +2891,7 @@ void producer_plugin_impl::switch_to_read_window() {
       [received_block=&_received_block, pending_block_num, ro_window_deadline=_ro_window_deadline]() {
          return fc::time_point::now() >= ro_window_deadline || (received_block->load() >= pending_block_num); // should_exit()
       });
+   chain.set_to_read_window();
    chain.set_db_read_only_mode();
    _ro_all_threads_exec_time_us = 0;
 
@@ -2988,11 +2991,11 @@ bool producer_plugin_impl::push_read_only_transaction(transaction_metadata_ptr t
       // When executing a read-only trx on the main thread while in the write window,
       // need to switch db mode to read only.
       auto db_read_only_mode_guard = fc::make_scoped_exit([&]{
-         if( app().executor().is_write_window() )
+         if( chain.is_write_window() )
             chain.unset_db_read_only_mode();
       });
 
-      if ( app().executor().is_write_window() ) {
+      if ( chain.is_write_window() ) {
          chain.set_db_read_only_mode();
          auto idle_time = fc::time_point::now() - _idle_trx_time;
          _time_tracker.add_idle_time( idle_time );
@@ -3012,7 +3015,7 @@ bool producer_plugin_impl::push_read_only_transaction(transaction_metadata_ptr t
          _ro_exhausted_trx_queue.push_front( {std::move(trx), std::move(next)} );
       }
 
-      if ( app().executor().is_write_window() ) {
+      if ( chain.is_write_window() ) {
          _idle_trx_time = fc::time_point::now();
       }
    } catch ( const guard_exception& e ) {