solve the nodejs heap allocation issue (appears around 100 samples)

workflow/README.md

@@ -14,6 +14,29 @@ To run the full workflow:
 NOTE: the examples below assume `bash`. In particular, it won't work with `zsh` 
 (which is the dafault on newer macOS)! Because, you know, reasons...
 
+### Some measurements
+
+Approximate time to run this on an M2 (8+4 cores), with 10 samples:
+
+- compiling the circuit: 8 seconds 
+- circuit-specific setup (with 1 contributor): 85 seconds
+- size of the `.zkey` file (only 1 contributor): 110 megabytes
+- proving with `snarkjs` (slow): 7.7 seconds
+
+Same with 50 samples:
+
+- compiling: 37 seconds
+- circuit-specific setup: ~420 seconds
+- `.zkey` file: 525 megabytes
+- snarkjs prove: 34 seconds
+
+And with 100 samples:
+- compiling: 76 seconds
+- circuit-specific setup: ~1000 seconds
+- `.zkey` file
+- snarkjs prove: 76 seconds
+
+
 ### Preliminaries
 
 - install `circom`, `snarkjs`, `rapidsnark`: <https://docs.circom.io/getting-started/installation>
@@ -71,6 +94,11 @@ the whole process.
     $ snarkjs groth16 setup proof_main.r1cs ../../ceremony/powersOfTau28_hez_final_21.ptau proof_main_0000.zkey
     $ snarkjs zkey contribute proof_main_0000.zkey proof_main_0001.zkey --name="1st Contributor Name"
 
+NOTE: with large circuits, javascript can run out of heap. You can increase the
+heap limit with:
+
+    $ NODE_OPTIONS="--max-old-space-size=8192" snarkjs groth16 setup <...>
+
 You can add more contributors here if you want.
 
 Finally rename the last contributions result and export the verification key:

workflow/params.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-MAXDEPTH=16        # maximum depth of the slot tree 
+MAXDEPTH=32        # maximum depth of the slot tree 
 MAXSLOTS=256       # maximum number of slots  
 CELLSIZE=2048      # cell size in bytes 
 BLOCKSIZE=65536    # block size in bytes 

workflow/setup.sh

@@ -14,19 +14,23 @@ ${NIMCLI_DIR}/cli $CLI_ARGS -v --circom=${CIRCUIT_MAIN}.circom
 
 # --- compile the circuit ---
 
-circom --r1cs --wasm --O2 -l${CIRCUIT_DIR} ${CIRCUIT_MAIN}.circom
+time circom --r1cs --wasm --O2 -l${CIRCUIT_DIR} ${CIRCUIT_MAIN}.circom
 
 # --- circuit specific setup ---
 
-snarkjs groth16 setup ${CIRCUIT_MAIN}.r1cs $PTAU_PATH ${CIRCUIT_MAIN}_0000.zkey
+start=`date +%s`
 
+NODE_OPTIONS="--max-old-space-size=8192" snarkjs groth16 setup ${CIRCUIT_MAIN}.r1cs $PTAU_PATH ${CIRCUIT_MAIN}_0000.zkey
 echo "some_entropy_75289v3b7rcawcsyiur" | \
-snarkjs zkey contribute ${CIRCUIT_MAIN}_0000.zkey ${CIRCUIT_MAIN}_0001.zkey --name="1st Contributor Name"
+NODE_OPTIONS="--max-old-space-size=8192" snarkjs zkey contribute ${CIRCUIT_MAIN}_0000.zkey ${CIRCUIT_MAIN}_0001.zkey --name="1st Contributor Name"
 
 rm ${CIRCUIT_MAIN}_0000.zkey
 mv ${CIRCUIT_MAIN}_0001.zkey ${CIRCUIT_MAIN}.zkey
 snarkjs zkey export verificationkey ${CIRCUIT_MAIN}.zkey ${CIRCUIT_MAIN}_verification_key.json
 
+end=`date +%s`
+echo "The circuit specific setup took `expr $end - $start` seconds."
+
 # --- finish the setup ---
 
 cd $ORIG