【移动应用开发技术】Android Web3j OOM解决详解

【移动应用开发技术】AndroidWeb3jOOM解决详解

在Android客户端使用Web3j创建钱包、导入钱包时都可能会产生OOM，相关issue在Github上已经有所提及：/web3j/web3j/issues/299。这个问题在Web3j3.0版本以前是没有的，由于新版的Web3j使用spongycastle库替换了lambdaworks库，虽然在效率上提升了速度，但存在Android端的兼容性问题。本项目代码地址：/uncleleonfan/WalletOOM.git创建钱包OOM解决

在创建钱包时，如果创建一个FullWallet，则会导致OOM：Log如下：

"Causedby:java.lang.OutOfMemoryError:Failedtoallocatea1036byteallocationwith16777216freebytesand48MBuntilOOM;failedduetofragmentation(requiredcontinguousfree16384bytesforanewbufferwherelargestcontiguousfree8192bytes)",

"\tatorg.spongycastle.util.Arrays.clone(Arrays.java:602)",

"\tatorg.spongycastle.crypto.generators.SCrypt.SMix(SCrypt.java:126)",

"\tatorg.spongycastle.crypto.generators.SCrypt.MFcrypt(SCrypt.java:87)",

"\tatorg.spongycastle.crypto.generators.SCrypt.generate(SCrypt.java:66)",

"\tatorg.web3j.crypto.Wallet.generateDerivedScryptKey(Wallet.java:136)",

"\tatorg.web3j.crypto.Wallet.create(Wallet.java:74)",

"\tatorg.web3j.crypto.Wallet.createStandard(Wallet.java:93)",

"\tatorg.web3j.crypto.WalletUtils.generateWalletFile(WalletUtils.java:61)"

"Causedby:java.lang.OutOfMemoryError:Failedtoallocatea1036byteallocationwith16777216freebytesand48MBuntilOOM;failedduetofragmentation(requiredcontinguousfree16384bytesforanewbufferwherelargestcontiguousfree8192bytes)",

"\tatorg.spongycastle.util.Arrays.clone(Arrays.java:602)",

"\tatorg.spongycastle.crypto.generators.SCrypt.SMix(SCrypt.java:126)",

"\tatorg.spongycastle.crypto.generators.SCrypt.MFcrypt(SCrypt.java:87)",

"\tatorg.spongycastle.crypto.generators.SCrypt.generate(SCrypt.java:66)",

"\tatorg.web3j.crypto.Wallet.generateDerivedScryptKey(Wallet.java:136)",

"\tatorg.web3j.crypto.Wallet.create(Wallet.java:74)",

"\tatorg.web3j.crypto.Wallet.createStandard(Wallet.java:93)",

"\tatorg.web3j.crypto.WalletUtils.generateWalletFile(WalletUtils.java:61)"

generateFullNewWalletFile里面会调用createStandard创建钱包，使用N_STANDARD，P_STANDARD来配置加密强度，直接影响需使用的内存大小，最终导致OOM的发生。解决方法非常简单，创建一个LightWallet即可：generateLightNewWalletFile会调用createLight来创建一个轻钱包，使用N_LIGHT，P_LIGHT，他们在数值上相对较小，所以不会OOM。我们可以对比一下N_STANDARD和P_STANDARD，N_LIGHT和P_LIGHT的大小：导入钱包OOM解决

当我们导入一个轻钱包时，不会产生OOM，但导入不是一个轻钱包时，则有可能产生OOM。例如，我们使用Imtoken创建一个钱包并导出Keystore，Keystore如下：

{"address":"9a2e2419f3af050d4730f80e7a65b9f8deb5e16f","crypto":{"cipher":"aes-128-ctr","cipherparams":{"iv":"eaccea79c27a91e307f24988186ef21a"},"ciphertext":"a163e532edf2d76beaee5c26fd2c2fab071a9cb37627aa185ac89e223e41ab97","kdf":"scrypt","kdfparams":{"dklen":32,"n":65536,"p":1,"r":8,"salt":"6a847392a029553f4152dea7bb0b6fb0ac9eec29f55e572fe94603182f5ed7f1"},"mac":"3fad2a31e18c611b10df84db9ae368ce2e189b5c35e9f111e40ca4b4bfb02491"},"id":"032c47c2-c7b7-46f8-a3f7-f526580f6f09","version":3}

{"address":"9a2e2419f3af050d4730f80e7a65b9f8deb5e16f","crypto":{"cipher":"aes-128-ctr","cipherparams":{"iv":"eaccea79c27a91e307f24988186ef21a"},"ciphertext":"a163e532edf2d76beaee5c26fd2c2fab071a9cb37627aa185ac89e223e41ab97","kdf":"scrypt","kdfparams":{"dklen":32,"n":65536,"p":1,"r":8,"salt":"6a847392a029553f4152dea7bb0b6fb0ac9eec29f55e572fe94603182f5ed7f1"},"mac":"3fad2a31e18c611b10df84db9ae368ce2e189b5c35e9f111e40ca4b4bfb02491"},"id":"032c47c2-c7b7-46f8-a3f7-f526580f6f09","version":3}

可以看到，其中n为65536，p为1，而轻钱包的n为1<<12,即2的12次方，4096，所以这不是一个轻钱包。我们将该Keystore作为一个json文件push到SD卡中，然后使用Web3j进行导入：发现同样会OOM：

Causedby:java.lang.OutOfMemoryError:Failedtoallocatea1036byteallocationwith13588800freebytesand12MBuntilOOM;failedduetofragmentation(requiredcontinguousfree16384bytesforanewbufferwherelargestcontiguousfree12288bytes)

atorg.spongycastle.util.Arrays.clone(Arrays.java:602)

atorg.spongycastle.crypto.generators.SCrypt.SMix(SCrypt.java:126)

atorg.spongycastle.crypto.generators.SCrypt.MFcrypt(SCrypt.java:87)

atorg.spongycastle.crypto.generators.SCrypt.generate(SCrypt.java:66)

atorg.web3j.crypto.Wallet.generateDerivedScryptKey(Wallet.java:136)

atorg.web3j.crypto.Wallet.decrypt(Wallet.java:214)

atorg.web3j.crypto.WalletUtils.loadCredentials(WalletUtils.java:112)

Causedby:java.lang.OutOfMemoryError:Failedtoallocatea1036byteallocationwith13588800freebytesand12MBuntilOOM;failedduetofragmentation(requiredcontinguousfree16384bytesforanewbufferwherelargestcontiguousfree12288bytes)

atorg.spongycastle.util.Arrays.clone(Arrays.java:602)

atorg.spongycastle.crypto.generators.SCrypt.SMix(SCrypt.java:126)

atorg.spongycastle.crypto.generators.SCrypt.MFcrypt(SCrypt.java:87)

atorg.spongycastle.crypto.generators.SCrypt.generate(SCrypt.java:66)

atorg.web3j.crypto.Wallet.generateDerivedScryptKey(Wallet.java:136)

atorg.web3j.crypto.Wallet.decrypt(Wallet.java:214)

atorg.web3j.crypto.WalletUtils.loadCredentials(WalletUtils.java:112)

通过log可以看出来，这里和创建钱包的OOM是一样的，都是最后调用generateDerivedScryptKey后导致:创建钱包可以创建一