PyPlot memory deallocation problem

Hi,

when batch saving multiple figures with 'savefig()' a large amount of memory is
allocated and I am not able to free it afterwards without closing my julia session.

Basically I am doing:

``` julia
for ff=101:150
figure(1)
PyPlot.clf()
imshow(imagg,extent=[0,350,0,580],aspect=1);
imshow(gridG[1:18,1:35,ff],interpolation="bicubic",cmap="jet",origin="lower",extent=[14,339,158,300],alpha=.5,aspect=.8)
PyPlot.autoscale("off")
plt.axis("off")
plt.title("Absolute value @" *string(ff)* " Hz")
savefig("~/pianoMeas1/klavierKlopfTest_"*string(ff)*".png");
plt.close()
end
```

The memory usage before the loop is ~2gb, after the loop it is ~4gb.

I also tried

``` julia
figurN=open("~/pianoMeas1/klavierKlopfTest_"*string(ff)*".png","w")
plt.savefig(figurN);
close(figurN)
```

giving the same result.

When overwriting existing files the memory usage stays constant so I believe the
"memory-overflow" occurs while allocating space for the file, but this is just a shot in the dark.

My julia version is:

``` julia
versioninfo()
Julia Version 0.4.0-dev+2496
Commit 89f89e1* (2015-01-05 09:04 UTC)
DEBUG build
Platform Info:
System: Linux (x86_64-unknown-linux-gnu)
CPU: Intel(R) Core(TM) i7-2600K CPU @ 3.40GHz
WORD_SIZE: 64
BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY Sandybridge)
LAPACK: libopenblas
LIBM: libopenlibm
LLVM: libLLVM-3.3
```

Any ideas, pointers are appreciated as I am not shure where to start debugging this.