c# - Are expression trees thread-safe? -

i want cache expressions generated dynamically (with linqkit) in order pass them where clause part of entity framework query.

so have like

private static expression<func<t, bool>> _expression; // gets value @ runtime  public iqueryable<t> apply(iqueryable<t> query)  {             return query.where(_expression); // here _expression has value } 

is safe multiple threads call apply , execute queries in parallel? expression<tdelegate> class thread-safe?

docs give standard "any public static (shared in visual basic) members of type thread safe..."

expression trees immutable. however, can refer things do change, e.g.

using system; using system.collections.generic; using system.linq; using system.linq.expressions;  public class test {     static void main()     {         int multiplier = 3;         iqueryable<int> values = new list<int> { 1, 2 }.asqueryable();         expression<func<int, int>> expression = x => x * multiplier;          // prints 3, 6         foreach (var item in values.select(expression))         {             console.writeline(item);         }          multiplier = 5;          // prints 5, 10         foreach (var item in values.select(expression))         {             console.writeline(item);         }     } } 

if expression tree refers things don't change, should fine. case in situations.

if expression tree does refer mutable state, if 1 thread mutates state, other threads applying expression tree may or may not see change, in normal way of memory models.