Test tcp deadlock fixes (#14946)

This fix follows #14667 and #14886

Several tests pipelined large numbers of commands on deferring clients
without draining replies. That can fill buffers and stall progress.

Fix by draining replies every 500 pipelined requests to avoid TCP
stalls.

---------

Co-authored-by: oranagra <oran@redislabs.com>

tests/cluster/tests/17-diskless-load-swapdb.tcl

@@ -54,9 +54,12 @@ test "Main db not affected when fail to diskless load" {
     set rd [redis_deferring_client redis $master_id]
     for {set j 0} {$j < $num} {incr j} {
         $rd set $j $value
-    }
-    for {set j 0} {$j < $num} {incr j} {
-        $rd read
+
+        if {($j + 1) % 500 == 0} {
+            for {set i 0} {$i < 500} {incr i} {
+                $rd read
+            }
+        }
     }
 
     # Start the replica again

tests/helpers/gen_write_load.tcl

@@ -22,13 +22,18 @@ proc gen_write_load {host port seconds tls {key ""} {size 0} {sleep 0}} {
     set start_time [clock seconds]
     set r [redis $host $port 1 $tls]
     $r client setname LOAD_HANDLER
-    $r select 9
+    $r read
+    catch {
+        $r select 9
+        $r read
+    } ;# select 9 will fail in cluster mode
 
     # fixed size value
     if {$size != 0} {
         set value [string repeat "x" $size]
     }
 
+    set count 0
     while 1 {
         if {$size == 0} {
             set value [expr rand()]
@@ -39,13 +44,28 @@ proc gen_write_load {host port seconds tls {key ""} {size 0} {sleep 0}} {
         } else {
             $r set $key $value
         }
+        
+        incr count
+        if {$count % 500 == 0} {
+            for {set i 0} {$i < 500} {incr i} {
+                $r read
+            }
+            set count 0
+        }
+
         if {[clock seconds]-$start_time > $seconds} {
-            exit 0
+            break
         }
         if {$sleep ne 0} {
             after $sleep
         }
     }
+    
+    # Read remaining replies
+    for {set i 0} {$i < $count} {incr i} {
+        $r read
+    }
+    exit 0
 }
 
 gen_write_load [lindex $argv 0] [lindex $argv 1] [lindex $argv 2] [lindex $argv 3] [lindex $argv 4] [lindex $argv 5] [lindex $argv 6]

tests/unit/memefficiency.tcl

@@ -345,7 +345,7 @@ run_solo {defrag} {
             # create big keys with 10k items
             # Use batching to avoid TCP deadlock
             set rd [redis_deferring_client]
-            set batch_size 1000
+            set batch_size 100
             for {set j 0} {$j < 10000} {incr j} {
                 $rd hset bighash $j [concat "asdfasdfasdf" $j]
                 $rd lpush biglist [concat "asdfasdfasdf" $j]

tests/unit/type/set.tcl

@@ -1026,7 +1026,22 @@ foreach type {single multiple single_multiple} {
                 break
             }
         }
-        r srem $myset {*}$members
+        r deferred 1
+        set count 0
+        foreach m $members {
+            r srem $myset $m
+            incr count
+            if {$count == 500} {
+                for {set i 0} {$i < 500} {incr i} {
+                    r read
+                }
+                set count 0
+            }
+        }
+        for {set i 0} {$i < $count} {incr i} {
+            r read
+        }
+        r deferred 0
     }
 
     proc verify_rehashing_completed_key {myset table_size keys} {