Strange behavior of function (memory leaks)

Question

I have some funtion:

GetOptimalWarpingPathMod[cumulativeCostMatrix_List, a_Integer, 
   b_Integer] := Module[{optimalPath, j, i, min, argMin},
   {i, j} = {a, b};
   optimalPath = Reap@While[(i >= 3) && (j >= 2),
      min = 
       Min[cumulativeCostMatrix[[i, j - 1]], 
        cumulativeCostMatrix[[i - 1, j - 1]], 
        cumulativeCostMatrix[[i - 2, j - 1]]];
      Switch[min,
       cumulativeCostMatrix[[i, j - 1]], argMin = {i, j - 1}; j--,
       cumulativeCostMatrix[[i - 1, j - 1]], argMin = {i - 1, j - 1}; 
       i--; j--,
       cumulativeCostMatrix[[i - 2, j - 1]], argMin = {i - 2, j - 1}; 
       i -= 2; j--,
       _, Throw["Error in GetOptimalWarpingPathNewMod"]
       ];
      Sow@argMin;
      ];
   optimalPath = 
    If[Length[optimalPath[[2]]] == 0, {}, optimalPath[[2, 1]]];
   PrependTo[optimalPath, {a, b}];
   optimalPath = Reverse@optimalPath;
   optimalPath
   ];

When I call it with random argument this leads to memory leaks:

$HistoryLength = 1;
someMatrix = RandomReal[{0, 20}, {10, 5}];
    memoryBefore = MemoryInUse[];
    Do[
      GetOptimalWarpingPathMod[someMatrix , Length[someMatrix ], 
       Ordering[someMatrix [[-1]]][[1]]],
      {i, 1, 10}];
    MemoryInUse[] - memoryBefore
    (*17752*)

But calling this function with predefined matrix all work fine

savedMatrix={{3.3004394437748807`,10.881946255573773`,4.362690908144572`,7.407440543303238`,7.345486257827773`},{14.508362563589763`,0.7356685771730973`,8.779141880113663`,14.969579494157415`,8.685346276624468`},{14.917882497227396`,17.430051988389053`,10.513304852635628`,16.791683365979523`,12.646147419315149`},{1.0588495204942632`,2.2005278583930767`,16.75277676811745`,4.0963643230729865`,13.369846181008235`},{14.413222169933519`,12.715945901646649`,12.488814903450923`,0.5015257662166803`,18.833930414984806`},{10.97588310006406`,8.811907048532749`,13.721241067651995`,17.829727310320855`,2.9585195950653898`},{1.85685418882683`,13.50702995493117`,16.501883534317372`,12.896932254223422`,14.724301159710564`},{8.246316747888361`,8.819447634430265`,11.769957506935448`,6.171909927482631`,12.075720584292299`},{2.3538532552195015`,18.372378238597122`,1.767319259063889`,8.244194544322362`,1.239398836296214`},{10.33557094657684`,11.650188299063093`,4.182059630971807`,17.839911646054595`,8.060657545219925`}};
memoryBefore = MemoryInUse[];

Do[
  GetOptimalWarpingPathMod[savedMatrix, Length[savedMatrix], 
   Ordering[savedMatrix[[-1]]][[1]]],
  {i, 1, 10}];
MemoryInUse[] - memoryBefore
(*8*)

What difference in that function calling?

EDIT

Of cource this function do nothing. But there the same problem

GetOptimalWarpingPathSimple[cumulativeCostMatrix_List, a_Integer, 
   b_Integer] := Module[{optimalPath, j, i, min, argMin},
   {i, j} = {a, b};
   While[(i >= 3) && (j >= 2),
    min = 
     Min[cumulativeCostMatrix[[i, j - 1]], 
      cumulativeCostMatrix[[i - 1, j - 1]], 
      cumulativeCostMatrix[[i - 2, j - 1]]];
    Switch[min,
     cumulativeCostMatrix[[i, j - 1]], argMin = {i, j - 1},
     cumulativeCostMatrix[[i - 1, j - 1]], argMin = {i - 1, j - 1},
     cumulativeCostMatrix[[i - 2, j - 1]], argMin = {i - 2, j - 1}
     ];
    RandomChoice[{j--, {i--; j--}, {i -= 2; j--}}];
    ];
   ];

PS: probably problem in Switch fucntion becouse when I comment it the is no memory leaks

Answer 1

I don't know why, but replacing Switch with nested If solved the problem of leaking memory.