MaxListenersExceededWarning encountered when running with Web3

[adrianmcli]

For more detailed history: web3/web3.js#1648

When running Ganache provider (for my tests) and then subsequently interacting them with Web3.js, I get warnings like the following:

(node:38062) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 data listeners added. Use emitter.setMaxListeners() to increase limit

According to this specific comment, the issue seems to be due to the Ganache Provider.

Interestingly, @cgewecke suppressed these warnings in Truffle in this PR: trufflesuite/truffle#1088

Not exactly sure if this belongs here, but I believe it is worth the investigation.

[mikeseese]

I can reproduce this by running the test/call test every time.

Here is a stacktrace of the warning:

(node:11601) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 data listeners added. Use emitter.setMaxListeners() to increase limit
    at _addListener (events.js:243:17)
    at Provider.addListener (events.js:259:10)
    at RequestManager.setProvider (/.../ganache-core/node_modules/web3-core-requestmanager/src/index.js:98:23)
    at Object.packageInit (/.../ganache-core/node_modules/web3-core/src/index.js:57:33)
    at Contract (/.../ganache-core/node_modules/web3-eth-contract/src/index.js:63:10)
    at new Contract (/.../ganache-core/node_modules/web3-eth/src/index.js:148:22)
    at Contract.clone (/.../ganache-core/node_modules/web3-eth-contract/src/index.js:560:12)
    at Object.contractDeployFormatter (/.../ganache-core/node_modules/web3-eth-contract/src/index.js:878:57)
    at Object.callback (/.../ganache-core/node_modules/web3-core-method/src/index.js:323:70)
    at sendTxCallback (/.../ganache-core/node_modules/web3-core-method/src/index.js:487:29)
    at /.../ganache-core/node_modules/web3-core-requestmanager/src/index.js:147:9
    at Object.intermediary [as callback] (/.../ganache-core/lib/provider.js:116:5)
    at self.engine.sendAsync (/.../ganache-core/lib/provider.js:171:12)
    at /.../ganache-core/node_modules/web3-provider-engine/index.js:152:9
    at /.../ganache-core/node_modules/async/internal/once.js:12:16
    at replenish (/.../ganache-core/node_modules/async/internal/eachOfLimit.js:61:25)
    at /.../ganache-core/node_modules/async/internal/eachOfLimit.js:71:9
    at eachLimit (/.../ganache-core/node_modules/async/eachLimit.js:43:36)
    at /.../ganache-core/node_modules/async/internal/doLimit.js:9:16
    at end (/.../ganache-core/node_modules/web3-provider-engine/index.js:127:5)
    at /.../ganache-core/lib/statemanager.js:271:5
    at /.../ganache-core/lib/blockchain_double.js:1105:9
    at process._tickCallback (internal/process/next_tick.js:61:11)

[mikeseese]

The only correct path forward within ganache (I believe that this is really a problem in web3.js which is adding listeners a little haphazardly) is to overload the on() function in the ganache provider and do some stuff to prevent the warning. Suppressing the warnings like the truffle PR is definitely not a great approach

[mikeseese]

Seems like this issue is being dropped